During a March 2021 hearing of the Senate Armed Services Committee, the outgoing combatant commander of US Indo-Pacific Command, Admiral Philip Davidson, warned that the People’s Republic of China was accelerating the pursuit of military capabilities that could be used to seize Taiwan, by force if necessary. “I think the threat is manifest during this decade,” Davidson testified, “in fact, in the next six years.”1 The assessment, offered in a routine hearing in response to a question posed by Senator Dan Sullivan, Republican of Alaska and a Marine Corps reservist, reflected a bipartisan shift over the course of several presidential administrations toward a more confrontational stance to counter an increasingly assertive China.
Davidson’s remarks anticipated forthcoming policy statements from the Biden administration that warned of a “decisive decade” of strategic competition among major powers and identified the threat of military action against Taiwan as the Defense Department’s “pacing scenario,” as a senior civilian Pentagon official testified at the Senate Foreign Relations Committee the following December.2 Testimony from the director of the Central Intelligence Agency, William Burns, echoed assessments from General Mark Milley, chairman of the Joint Chiefs of Staff, clarifying that the 2027 timeframe was a benchmark by which Chinese military leaders had been instructed to develop and modernize capabilities that could be used to seize Taiwan, not an firm deadline by which such an imminent invasion would occur.3 Defense leaders and analysts nevertheless seized on the combatant commander’s remarks and began anchoring debates about Washington’s preparedness for a potential conflict with China around what became known as the “Davidson window.”4 Subsequently, many defense leaders built on this potential timeframe; the Chief of Naval Operations, for example, stated in her Navigation Plan “how the Navy will be ready for sustained high-end joint and combined combat by 2027.”5
This episode joins several high-profile moments during congressional hearings in which the statements of senior military officers seemingly influenced the contours of debates over pressing defense and national security issues. In most instances, but not all, these statements have reinforced assessments offered by civilian policymakers within the executive branch and national security experts outside government. In some instances, presidential administrations have deployed service chiefs or combatant commanders to Capitol Hill to make the case for increased defense spending. In other cases, members of Congress from both parties have used their questions to expose differences between military judgments and policymakers’ preferences, as when General Eric Shinseki, Army Chief of Staff, testified in February 2003 that the United States could need “several hundred thousand troops” to secure post-invasion Iraq, an estimate at odds with plans advanced by Secretary of Defense Donald Rumsfeld and other officials in the George W. Bush administration.6
Such moments on Capitol Hill are widely publicized, but it remains unclear how frequently they occur, whether statements are walked back or not, and just how representative statements are of the broader dialogue between the legislative and executive branches over defense policy. Scholars have long recognized Congress’s role in shaping defense budgets and conducting oversight over the armed forces, but few studies have examined how the witnesses that congressional committees choose to call to testify can inform members of Congress or shape congressional involvement in national security policy.
Different types of witnesses serve different functions in these hearings. This article discusses three types—civilian government officials, including political appointees and career civil servants; uniformed military officers, such as service chiefs and combatant commanders; and nongovernment experts—who each can offer different perspectives to Congress in national security debates. Even among Defense Department officials, those testifying have different interests, constituencies, and responsibilities that can span service branch hierarchies or cut across the regional or functional boundaries that organize the armed forces.7 The Defense Department is far from a monolith—it is one of the world’s largest organizations and has a vast global footprint. Organizations have distinct missions defined in law, which can create tension over resources. As a result, there are times when a person’s stance on a particular issue may depend on where they happen to sit, whether it be in a combatant command headquarters in Germany that is focused on deterring Russia and strengthening NATO, in a forward-deployed headquarters in a conflict zone using missiles to defend a partner country, or in an office in the Pentagon developing a strategy to redefine how the US military should fight.
Thus, we argue that the expertise Congress chooses to draw upon at any particular political moment can have important implications for the substance of national security debates, the time horizons associated with alternative resourcing investments, and the public’s perceptions of whether the proper purveyors of defense policy are civilian appointees in a suit or commissioned military officers in a uniform.
Whether Congress turns more frequently to civilian defense officials or uniformed military officers can also have significant consequences for civilian control of the armed forces in a democratic society. Both scholars and practitioners have warned that the privileging of military expertise and influence in these settings can distort the relationship between civilian superiors and military subordinates.8 Such concerns led some, like former Secretary of Defense Mark Esper, to argue that, in most cases, combatant commanders should testify before Congress or meet with members of their staff only with their civilian counterparts in the Office of the Secretary of Defense. “This would reaffirm civilian primacy and control of the military,” Esper wrote in his memoirs, “and give the necessary perspective of civilian leadership at the Pentagon to their congressional overseers.”9
When testifying on the Hill, senior military officers fulfill what Samuel Huntington called “representative” and “advisory” functions in justifying defense budgets or outlining the implications of alternative courses of action in ongoing conflicts.10 Congressional hearings, however, can confront service chiefs and combatant commanders with fraught tradeoffs between the need for candor in delivering professional military judgments to a coequal branch of government and the legal and normative imperatives of subordinating these views to civilians in the executive branch charged with making defense policy. Political appointees and other civilians, for their part, can testify more freely on matters of policy in these settings, but they may be reluctant to offer viewpoints that diverge substantially from those of uniformed officers, even when based on independent sources of expertise, out of respect for the institution or appreciation of the leadership challenge.11
This article, therefore, examines who testifies before Congress on matters of defense policy. Using an original dataset of over 6,500 witness appearances before the House Armed Services Committee (HASC) in the 94th (1975–76), 99th (1985–86), 104th (1995–96). and 107–114th (2001–2016) Congresses, we find that Congress has consistently turned to a mix of government civilians, senior military officers, and nongovernment experts when seeking testimony on defense matters.12 Broadly speaking, the balance between government civilian and military witnesses who appeared before the House Armed Services Committee remained largely stable in this dataset, tilting slightly in favor of civilian government witnesses over time, even when accounting for changes in committee party leadership, the increasing frequency of divided government, and rising partisan polarization within Congress. Apart from a higher proportion of uniformed military witnesses in the initial stages of the wars in Iraq and Afghanistan in the early 2000s, civilian government witnesses in our dataset make up a slightly growing share of HASC witnesses in the late 2000s and early 2010s. This development is a positive sign for civilian control of the military. Among uniformed military witnesses, HASC appearances by combatant commanders have increased over the last several decades relative to members of the Joint Chiefs of Staff, a change that reflects both the growth in number of combatant commands and their elevation in authority under the 1986 Goldwater-Nichols Act.13
While our findings are largely descriptive, they offer important implications for Congress’s role in overseeing the development and execution of defense policy. On one hand, Congress’s continued reliance on civilian officials and outside experts over time channels its investigative and oversight activity toward those policymakers vested with the authority to formulate and direct the implementation of defense policy. On the other hand, the persistence of these rates of participation by civilian and military witnesses in an era of growing partisan polarization increases the risk that service members will find themselves dragged into partisan bickering over even previously uncontroversial matters such as camouflage patterns on uniforms.
Our findings also contribute to several important debates in the study of national security policy. We advance scholarly knowledge of Congress’s role in shaping defense policy by identifying who the legislature turns to when informing itself on defense policy.14 Although previous work has examined what types of legislative, investigative, and oversight hearings the relevant House and Senate committees have conducted over time, few of these studies have systematically categorized the witnesses that appear at the hearing table.15 Studies of the institutional constraints that democracies face in war observe that the president’s co-partisans and opposition party elites within Congress can acquire information from the executive branch through hearings and investigations and can use this information to shape arguments either for or against the president’s national security agenda.16 Mobilization of elite opposition within Congress can send especially revealing signals to domestic and international audiences in ways that shape the credibility of the president’s threats.17 Understanding how Congress overcomes informational asymmetries relative to the executive branch enhances our understanding of the international signals sent from the domestic arena about everything from the depth of defense commitments abroad to the willingness of Congress to continue funding ongoing military operations. For these reasons, it matters who Congress asks for advice.
Unpacking which defense officials engage with Congress also illuminates an actor often overlooked in traditional principal-agent models of civil-military relations, but one that nevertheless plays an essential role in civilian control of the United States’ armed forces. Given the legislature’s role in funding, overseeing, and authorizing their activities, top uniformed military officers and politically appointed defense civilians must be responsive to requests for information and demands for testimony on regular oversight and investigative matters.18
Unpacking which defense officials engage with Congress also illuminates an actor often overlooked in traditional principal-agent models of civil-military relations, but one that nevertheless plays an essential role in civilian control of the United States’ armed forces.
In particular, understanding the conditions under which Congress calls certain types of officials to testify will inform our understanding of the process by which internal dissent or disagreement between civilian policymakers and service members can become public. Different types of officials will face various kinds of constraints in expressing public opposition to the president’s policies, but congressional hearings are among the few legitimate platforms for defense officials to voice dissent in regards to the sitting administration’s policies, particularly for uniformed personnel when asked directly for their professional military judgments by members of Congress.19 In some cases, the president’s political opponents in Congress have used hearings strategically to expose disagreements between presidential administration officials and the military brass over politically contentious policies.
Finally, our work informs recent scholarship on public opinion and the effects of partisan polarization on national security policy.20 Recent studies of public opinion have shown how statements from senior service members shape attitudes toward the use of force and the military more broadly.21 This study contributes to this work by identifying which types of witnesses appear before congressional defense committees more frequently when chaired by members from one party over another and under conditions of divided government.
The remainder of this article consists of four sections. First, we discuss the role of congressional committees in defense policymaking, and the range of expert witnesses that testify in hearings on defense matters. We outline our expectations prior to data collection on the frequency with which the different kinds of witnesses will appear over time. Next, we introduce our dataset and our coding methodology before presenting our results descriptively. The third section supplements our findings with a case study of the HASC’s September 2021 hearing on the US withdrawal from Afghanistan. Taken together, the testimonies of the civilian secretary of defense, the chairman of the Joint Chiefs of Staff, and the US Central Command combatant commander overseeing the withdrawal allows us to explore how the identities of the witnesses condition both the content of their remarks and the lines of questioning congressional members ask. We conclude by offering some implications of our findings and proposing topics for further research.
Congressional Oversight and Civilian Control of the Military
The Role of Committee Hearings
One of Congress’s main functions, in addition to drafting and passing legislation, is overseeing the executive branch’s operations. Article 1, Section 8 of the Constitution outlines fundamental national security roles for Congress that include the power to declare war, to raise and support armies, and to provide and maintain a navy. To fulfill these roles, Congress legislates requirements for studies and relies on hearings to gain expertise and ensure that the executive branch meets legislative intent. The committee system is robust, but “Congressional defense committees exercise a degree of direct access to career Department of Defense personnel—particularly senior military officers—that has no parallel in other committees’ relationships with the agencies they oversee.”22 The relationships can begin early because “defense committees routinely involve themselves more deeply in the organizational fabric of the armed services than other committees do in the career ranks of the agencies they oversee.”23 Thus, committee hearings are a key mechanism by which Congress conducts oversight of the federal bureaucracy and exercises civilian control over the military.
Congress also plays a key role in officer promotions and the confirmation process of senior uniform and civilian positions. For example, while discussing the confirmation process of a secretary of defense nominee, Senator Jack Reed of Rhode Island said: “The issue is not about confirmation or rejection of an individual nominee. It is about the Senate’s constitutional duty to advise, and consent based upon the facts, and not upon intimidation or blind political allegiance.”24 Thus, through the Senate confirmation process Congress can limit the president’s autonomy in the conduct of foreign affairs.25 It is common for senators in confirmation hearings to ask these nominees whether they will appear and testify before committees. To facilitate the frequency of communication between the Department of Defense and the Congress, the military services maintain offices of legislative affairs.
Despite these tools, Congress faces the challenge of delegating authority to the executive to make and implement policy. For the bureaucratic agents in the executive branch, this challenge is complicated by the fact that “government agencies also bear the burden of being institutions of American democracy,” as William Gormley and Steven Balla observe. They continue: “In democratic institutions, accountability to the American public and its elected representatives is a vital and unique concern. It would be troubling if policy were made by officials with little or no connection to the public.”26 In other words, “deference to specialized expertise can also mean a surrender of effective control.”27 Hearings make use of this specialized expertise and are thus a form of policy control.28
Fundamentally, committee hearings are a key mechanism by which Congress conducts oversight of the federal bureaucracy.
Fundamentally, committee hearings are a key mechanism by which Congress conducts oversight of the federal bureaucracy. These hearings occasionally break into the daily political news cycle with a high-profile witness, such as former FBI Director Robert Mueller, or comedian Jon Stewart, or even Sesame Street’s Elmo. Sometimes they might feature a clip-worthy gaffe: Representative Hank Johnson once expressed concern that additional US Marines might cause the island of Guam to capsize. But most of the time, these hearings occur under the radar, with hundreds of witnesses testifying before the House Armed Services Committee alone every year. These witnesses assist members of Congress in developing expertise to allocate defense resources, formulating defense policies, and ensuring that the executive branch is properly executing the national security policy for which Congress appropriates funds.
Partisanship adds an additional dimension to congressional oversight, particularly for the subset of leaders in the Defense Department that are nominated by the president: deputy undersecretaries and assistant secretaries within the Office of the Secretary of Defense; and secretaries, undersecretaries, and assistant secretaries within the services. Former Chairman of the Joint Chiefs of Staff (CJCS) General Martin Dempsey has argued that congressional oversight varies in regards to unified versus divided government: “When both the White House and the Senate are in the hands of the same party, oversight of senior military leaders in Washington is generally ‘kinder,’ perhaps even ‘gentler.’ When the White House and the Senate are in the hands of different parties, oversight is more contentious.”29
This difference makes defining oversight tricky.30 Mathew McCubbins and Thomas Schwartz famously characterize congressional oversight as reflecting either a “fire alarm” or “police patrol” model at any given time, both of which, broadly speaking, are used by Congress to fulfill its duty to check the executive branch.31 Committee hearings can play a role in both types. Regularly scheduled hearings—for example, military commanders provide annual testimony on national security challenges and adequacy to meet the challenges—can be considered routine police patrol monitoring. These hearings provide a consistent opportunity for members of Congress to understand threats in a particular region of the world, US strategy in that region, and capability gaps where congressional funding can help the US advance and defend national interests. Members and their staffs supplement this type of testimony with regular visits to military headquarters. Fire-alarm monitoring, by contrast, occurs through hearings called after issues are brought to light by whistleblowers or the media. Examples include hearings on sexual assault in the military, troops’ lack of protection from improvised explosive devices in Iraq, or the US withdrawal from Afghanistan.
Given the global reach and technical complexity of US defense policy, and the varied levels of familiarity with military matters prior to assuming their committee roles, members of Congress sometimes use hearings to bolster their knowledge. Members’ broader policy concerns inform resourcing decisions.32 In addition, hearings also allow committees to convey information publicly and provide elected officials to specialize and develop deeper policy expertise:
The committee may be able to control the hearing by determining who may testify, for how long, and in what order. Those who testify may withhold crucial information and even intentionally mislead both the committee and the Congress as a whole. However, the fact that non-committee members with privileged information usually testify in hearings is critical. While the floor may not find statements from the committee credible, it may be more inclined to believe testimony from experts. Experts may care more about establishing a reputation for correctly predicting policy outcomes rather than manipulating decision processes.33
Committees can act as mediators by situating expert testimony within the current political context. Committee hearings can take long-term views of defense policy but can also address issues of the day. According to Pat Towell, a longtime congressional reporter on defense issues, committees can merge substantive expertise with political know-how to highlight salient issues or compel a change in policy: “The greatest value added by the committees to the policy process is their potential to combine technical know-how with political acumen.”34
Both electoral and non-electoral goals drive congressional oversight.35 Certain committees are more highly valued than others, and members seek representation on committees for the benefits of their districts.36 National security committees such as the armed services committees allow members to play important roles in distributive politics, meaning they can ensure their districts benefit from weapons manufacturing.37 Non-legislative hearings can also be used by “legislative entrepreneurs”—those working outside the formal committee structure—to expand or shift committee jurisdiction.38
Members of Congress have less information on foreign and military policy than does the president. Members do visit military sites via congressional delegations (CODELs) that provide interpersonal interaction outside of the Beltway, but they have fewer opportunities to observe firsthand the impact of various policies especially relative to their understanding of domestic policy.39 Members also draw on important in-house sources of expertise: The Congressional Research Service and Congressional Budget Office are important sources of research and analysis, as is the Government Accountability Office, which is independent but reports to Congress.
Professional committee staffers develop significant expertise on relevant topics and conduct their own staff delegations (STAFFDELs). Still, the scope of national security policy is simply too big for members to develop expertise to make decisions on military force size, defense acquisition, and military law without learning from outside experts, including those in the executive branch who make and carry out policy daily. While there has been a recent uptick in veterans elected to Congress, direct military experience is still limited on Capitol Hill.40 Potential voters, regardless of party affiliation, rate candidates with military experience higher on defense issues.41 We have some evidence that veterans are more willing to exert control over the military in the form of restrictions on troop levels and requests for information, either because they are more comfortable in this policy arena, or believe they have more political cover to meddle in military affairs than do nonveterans.42 Nonveterans might be more inclined to defer to uniformed personnel, thus elevating the importance of testimony by uniformed personnel.
Whose Expertise?
To whom do members of Congress turn for expert testimony on defense policy? First, we note that committees may turn to nongovernment civilian experts, to members of the executive branch broadly, or to employees (civilian or military) within the Department of Defense. Indeed, the Defense Department can plausibly be thought of as a collection of organizations led by the secretary of defense, with significant roles played by the service secretaries, who organize, train, and equip the armed forces; the Joint Chiefs of Staff, who represent the interests of their respective service branches and whose chair serves as the president’s principal military advisor; and the combatant commanders, who oversee and execute joint operations within the regional and functional commands under their jurisdiction. Together, these officials within the Defense Department work from an annual budget of approximately $900 billion and lead nearly three million employees, including active-duty and reserve military personnel, and political appointees and career civilians. The Pentagon’s most visible leaders are in DC, but others are stationed across the United States and the world. For example, on nuclear issues, the head of US Strategic Command is in Nebraska; on Korean security issues, the head of US Forces Korea is in Seoul; and on European security issues, the senior US military leader is in Belgium fulfilling his NATO role.
Due to the deeply embedded constitutional norm of civilian control over the military, we might expect politically appointed civilians such as the undersecretaries of defense (currently research and engineering; acquisition and sustainment; policy; comptroller; personnel and readiness; and intelligence and security) to appear before Congress, because they play key roles in long-term issues and decisions such as acquisitions and strategy. High-level political appointees, however, may not be the best sources of information on their agencies, as they face their own challenges in guiding the bureaucracy while implementing the president’s political agenda. Below the political appointees, as analysts Morton H. Halperin, Priscilla Clapp, and Arnold Kanter write: “Career officials of an organization believe that they are in a better position than others to determine what capabilities they should have and how they should fulfill their mission. They attach extremely high priority to controlling their own resources so that they can use those resources to support the essence of the organization.”43
We also see several reasons to believe that expert testimony from military officers may hold more weight than that of a civilian with similar tenure in an organization. First, senior military officers, despite frequently changing positions and commands, have spent their entire careers in their service and have their own networks developed over their careers. This scenario can play out at the Pentagon where, as analysts Jim Cooper and Russell Rumbaugh note: “Services simply do not trust a political appointee enough to allow him to overrule their own plans,” which places those in uniform in a special position during legislative hearings.44 Additionally, military officers may hold a distinctive credibility. As former Secretary of Defense Bob Gates wrote:
Senior military officers have special credibility with Congress, the public, and even the media, and many are not shy about sharing their views when it comes to decisions to cut programs they favor—or even presidential decisions about operations. Senior civilians do the same, but they lack the special cachet of a four-star officer. When officers speak out publicly, people listen, often to the chagrin of presidents. . . . And because, in the confirmation process, every senior officer has to promise Congress that he or she will always provide them with his or her candid professional military opinion, testimony by senior officers often creates tension with the White House.45
A survey experiment found that statements by senior officers focused on issues within their area of expertise can shift public opinion, and this shift can happen without causing negative effects for the military institution.46 Administrations harness this stature in support of policy positions, thereby thrusting military leaders into the policy process.47 This approach can be precarious, according to David Barno and Nora Bensahel: “If their advice comes to be seen as compromised by partisanship, the nation’s elected leaders will not be able to objectively assess their military options, and their life-and-death decisions about when and how to use force will suffer immeasurably as a result.” 48
A survey experiment found that statements by senior officers focused on issues within their area of expertise can shift public opinion, and this shift can happen without causing negative effects for the military institution.
Within the military, the services and the unified combatant commands have their own authorities in law and sometimes offer distinct perspectives on questions of national security and defense policy.49 Military forces are developed through training and equipping by the military services such as the Navy but are employed by combatant commands such as US Indo-Pacific Command.50 This distinction is important since the military does more than fight and win the nation’s wars; it serves as a valuable tool of international politics, plays a significant role in domestic politics, and often consumes the largest share of federal discretionary spending.51 While the services feature strong personalities and are very influential within DoD, combatant commanders can also play important roles in policy formulation, including the Indo-Pacific Commander with respect to China policy and the European Commander on NATO policy.52
The 1986 Goldwater-Nichols Act fundamentally changed US civil-military relations by both elevating the chairman relative to the other members of the Joint Chiefs,53 and increasing the authority of combatant commanders. As analyst Christopher Fettweis noted, “combatant commanders have long been employed as mouthpieces for the administration’s policies in testimony . . . [and] have always been able to have some effect on the long-term direction of foreign policy.”54 Likewise, combatant commanders are aware of the influence they can bring to policy and spending decisions. General Wesley Clark, who served as a combatant commander and later ran for president, wrote:
From the beginning of my tour of duty, I had made it a practice to see every visiting congressional delegation, usually by flying in to link up with them wherever they were, and to convey my personal view of the problems and progress in the theater. While I had complete confidence in my commanders at each location, none had the personal engagement with the leaders in Europe that I did. The Congress, I had found, depended heavily on personal relationships.55
A military officer’s role in policy formulation can be precarious, as highly politicized militaries can undermine the quality of democracy.56 At times, this situation has sparked a disciplinary debate on whether US foreign policy has been militarized.57 Therefore, who is called to testify becomes an important input to how members of Congress make decisions. Others have studied committee witnesses to understand how Congress interacts with the Department of Defense over budget issues.58 These previous studies collected data on the number of hearings and the number of witnesses who testified each fiscal year, and whether these witnesses came from the Department of Defense, elsewhere in the federal government, or outside of government. Our new dataset builds on this previous work by providing significantly more granularity in the categorization of witnesses.
House Armed Services Committee Witnesses, 1975–2016
The debates outlined above highlight the importance of understanding who testifies to Congress, and who thus plays a critical role in informing, shaping, and legitimating defense policy and national security decision-making. We therefore collected data on over 6,500 witnesses who appeared before the House Armed Services Committee (HASC) using publicly available hearing transcripts.59
We collected data for the 94th, 99th, 104th, and 107th–114th Congresses. These most recent Congresses cover the post-9/11 years (2001–2016), while the older Congresses (1975–76, 1985–86, and 1995–96) allow for historical comparison. Of note, the HASC was renamed the House National Security Committee during the 104th Congress but the name HASC was returned by the following Congress; for our purposes we will refer to all as HASC. We categorized witnesses as follows:
- government vs. nongovernment witnesses
- within the government: military vs. civilian witnesses
- within civilian organizations: witnesses from the Office of the Secretary of Defense (OSD) vs. the service departments
- within the military: witnesses from the Joint Chiefs of Staff vs. combatant commanders
We believe that understanding who testifies before Congress will help us understand congressional oversight of the military and military policy as it relates to both bureaucratic politics and civil-military relations. Our focus on the HASC offers several advantages. First, committees in the House of Representatives experience a more regularized turnover in leadership and membership than their counterparts in the Senate. To the extent that increased rates of divided government and partisan polarization shape the kinds of witnesses Congress calls to testify, these effects would be more visible in the HASC compared with its Senate counterpart, the SASC. Second, representatives typically represent smaller constituencies than senators and must therefore compete more for media coverage within a larger legislative body. HASC leaders may therefore be tempted to draw on witnesses, particularly from the military, who can command attention in public discourse.
We believe that understanding who testifies before Congress will help us understand congressional oversight of the military and military policy as it relates to both bureaucratic politics and civil-military relations.
These factors provide a compelling reason to expect to see changes in the HASC witness composition over time. If the data conforms to these expectations—that the witness roster does in fact change alongside these trends toward divided government and increased polarization—we cannot definitively say whether these trends are driving these changes. But if the data confounds these expectations—that is, if it finds that the share of civilian, military, and nongovernment witnesses remains relatively stable over time—we can have slightly more confidence that increased rates of divided government and partisan polarization are having less of an effect in shaping the witness roster in the very committee where we would expect to see them operating.60
Each observation in our dataset corresponds to one witness appearance at one hearing. Most hearings have multiple observations—one for each witness who testified. (A few hearings do not appear in our dataset because they called no witnesses.) Witnesses that appear in the dataset multiple times testified at multiple hearings. We subdivide these observations by Congress—for example, the 113th Congress met from January 3, 2013, to January 3, 2015, which we classify substantively as calendar years 2013 and 2014.
The number of witnesses testifying before the HASC varied significantly from Congress to Congress. The 99th Congress HASC saw testimony from 833 witnesses, for example, while the 107th Congress called only 481 witnesses (see table 1). In our sample, the mean number of witnesses in a Congress was 604, while the median was 596.
Based on the witness names and titles (obtained from witness biographies online when necessary and possible), we coded whether each witness was an employee of the federal government or a current member of the military, or both. For military witnesses, we also coded their rank, service, and whether they were a member of the Joint Chiefs of Staff or a combatant commander. Members of the reserve component were classified as military if they were testifying in their military capacity, and as civilian if they were testifying in a civilian capacity. For civilian government witnesses, we coded their department or agency and rank (secretary, assistant secretary, and so forth) where possible. We coded nongovernment witnesses as academic, former government, industry, advocacy group, state/local government, or other.
Who Testifies? Government Civilians, Uniformed Military, and Nongovernment Experts Witnesses at HASC Hearings over Time
Our top-level finding is that the share of civilian, military, and nongovernment witnesses called to testify before the HASC remained fairly stable over time, even accounting for increased occurrences of divided government and rising partisan polarization. Deviations from the typical proportion tended to correspond, instead, to structural and organizational shifts in the international and domestic political environment, as we explore in tables 1 and 2.
Table 1. HASC witnesses categorized by government affiliation and military status
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Table 2. HASC witnesses by Congress with descriptive data on Congresses
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Witnesses from Outside the Federal Government
HASC witnesses from outside the federal government make up a minority in all Congresses in our sample. Table 1 shows no real shift in the share of witnesses from outside the federal government over time. The 104th Congress has the highest percentage of nongovernment witnesses, at 36 percent, while the 109th has the lowest at 18 percent. The mean percentage of nongovernment witnesses in our sample is 25 percent, while the median is 22 percent. These non-federal-government witnesses come from a variety of sources: think tanks, universities, state and local governments, defense contractors (both weapons systems and services), unions, and service-member advocacy organizations. Many nongovernment witnesses previously served in the federal government. We speculate that any increase in the number of available experts from think tanks and the private sector has been offset by expansion in the defense bureaucracy that has increased the number of potential government witnesses.
As table 2 indicates, our data suggests that Congress may be slightly more likely to call nongovernment witnesses when the House and White House are controlled by different parties, though our data is only suggestive. The highest share of nongovernment witnesses appears in the 99th and 104th Congresses: a Democratic-controlled House during the Reagan administration, and a Republican-controlled House during the Clinton administration, respectively.
Civilian Government Witnesses
Unsurprisingly, for the HASC, civilian government witnesses (ranging from 24 to 43 percent of witnesses; see table 1) come primarily from the Department of Defense. Other Cabinet-level departments represented, however, include the Departments61 of Energy, State, Homeland Security, Veterans Affairs, Transportation, Commerce, Justice, Interior, Health and Human Services, Agriculture, and Labor. There are also witnesses from research organizations that report to Congress—the Congressional Research Service (CRS), Congressional Budget Office (CBO), and Government Accountability Office (GAO). A few witnesses are themselves members of Congress—representatives and senators—and a few are members of committee or subcommittee staffs (see table 3).
Table 3. Percentage of HASC civilian government witnesses by branch and department
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Of civilian witnesses from DOD, a majority (ranging from 56 to 78 percent) are from the OSD or subordinate defense agencies that report to OSD,62 rather than from the military service departments (see table 4). This distinction is important because the creation of the Defense Department was intended to channel service rivalry and reduce the influence of service secretaries. Every Congress received testimony from the secretary of defense and three service secretaries (Army, Navy, and Air Force) at least once (see table 5). In terms of rank, the most common civilian DOD witness in every Congress in our sample is an assistant secretary or deputy assistant secretary.
Table 4. Percentage of HASC DOD civilian witnesses by organization
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Note: Rows may not sum to 100 percent due to rounding.
Table 5. Testimony by secretary of defense and service secretaries
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Military Witnesses
The percentage of military witnesses out of total testimonies before the HASC ranges from a low of 31 percent in the 99th and 104th Congresses to a high of 55 percent in the 94th (see table 1). In terms of share of federal government witnesses, the incidence of military witnesses ranges from a low of 47 or 48 percent in the 99th, 104th, 110th, and 111th Congresses to a high of 70 percent in the 94th Congress.
We see an increase in military witnesses in the 107th to 109th Congresses (from 2001 to 2006), but there is not a clear and sustained pattern of higher proportions of military witnesses across the full post-9/11 era. The lowest shares of military witnesses in the 99th and 104th Congresses correspond to a decrease in Cold War tensions during Reagan’s second term, as well as during the period after the 1991 Gulf War but pre-9/11.
There appears to be no difference in the frequency with which Democratic- versus Republican-controlled HASCs call military witnesses. Our dataset suggests that Congress may call more military witnesses (in proportional terms) when the House and White House are controlled by the same party.
Testimony from commanders of the unified combatant commanders (COCOMs) rises steadily starting with the 99th Congress, after the passage of Goldwater-Nichols in 1986 (see table 6).63 Testimony from combatant commanders is particularly frequent during the 111th to 113th Congresses, covering the years from 2009 to 2014, when the US surged forces to Afghanistan. Testimony from members of the Joint Chiefs of Staff appears to fluctuate over our sample without a clear pattern.64 The increase in HASC appearances by combatant commanders—who are charged with developing plans and executing operations—over the last several decades relative to members of the Joint Chiefs of Staff likely reflects the growth in the number of combatant commanders and the elevation in their authority (particularly during wartime and other contingency operations) under the 1986 Goldwater-Nichols Act.
Table 6. Testimony by members of the Joint Chiefs of Staff and combatant commanders
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Our findings highlight, first, the complex interplay among civilian leaders, military officers, and congressional staff that all interact to shape defense policy. This interplay can be frustrating for members of Congress; as just one example, Senate Angus King of Maine once called for “one throat to choke” when it came to cybersecurity.
Second, our data suggests that Congress does need expertise to inform its legislative and appropriations work. The HASC appears to seek greater expert testimony during critical national security junctures and moments of great debate over US defense policy: military modernization in the 1980s, downsizing in the 1990s, and the military surges in Iraq and Afghanistan in the late 2000s and early 2010s.
Finally, our data shows a relative balance between the influence of service chiefs and combatant commanders. This balance illustrates one way that tensions between the two types of military leaders can appear in policymaking: Service chiefs tend to plan with twenty-year time horizons to solve future challenges, whereas combatant commanders are planning over the next three years to solve today’s challenges. Combatant commanders may even have an advantage in policymaking because they report directly to the secretary of defense whereas a service chief reports to a service secretary.
Case Study: September 2021 HASC Hearing on Afghanistan Withdrawal
To illustrate the range of roles that different types of witnesses can play in congressional hearings, we conduct here a case study of the House Armed Service Committee’s September 2021 hearing on the end of the US military mission in Afghanistan. This study analyzes the interactions between members of Congress and officials called to testify in what amounted to a “fire-alarm” oversight hearing regarding the end of America’s twenty-year conflict in Central Asia.65
We examine this case for several reasons. First, the witness list reflects the full range of DoD officials: Secretary of Defense Lloyd Austin, a politically appointed civilian from the Biden administration; General Mark Milley, then-chairman of the Joint Chiefs of Staff; and General Kenneth “Frank” McKenzie, then-commander of US Central Command, the combatant commander who was tasked with overseeing US military operations in the Middle East and Central Asia.
This hearing showcases these dynamics in the context of a nonroutine, investigative hearing convened by a committee chair, Representative Adam Smith (D-WA), from the president’s own political party in 2021. The hearing brought congressional focus and media attention to a politically contentious decision to withdraw all remaining US forces from Afghanistan as conditions on the ground deteriorated in the face of a Taliban advance, and ultimately, takeover. The willingness of a Democratic chair to convene an events-driven, “fire-alarm” oversight hearing to investigate the president of his own political party under a period of unified government reinforces our finding that the composition of HASC witnesses has been largely invariant to trends in divided government and growing polarization.
Republican members of the committee leveraged the appearance of both General McKenzie, as the uniformed combatant commander in charge of the area, and General Milley, as the chairman of the Joint Chiefs of Staff, to draw out these officers’ initial opposition to the Biden administration’s decision to withdraw all remaining forces. Smith anticipated this line of questioning, as he opened the hearing by acknowledging: “I know a lot of energy will be expended today trying to get these gentlemen to admit that they didn’t agree with the president’s decision. First of all, I never engage in that exercise because I believe the President—Democrat, Republican, no matter who it is—deserves the . . . unabridged advice of his or her commanders. I mean, you can’t give that if you are then going to have to go out in public and talk about it. But second of all, the president is the one in charge. This is ultimately what civilian control of the military means.”66
The HASC chair’s attempt to deter his colleagues from pursuing this line of inquiry was offset by the Republican ranking member, Representative Mike Rogers (R-AL), who asked General Milley whether it had been his “professional military judgment” in January 2021—before President Biden announced his withdrawal decision in April—that the United States should maintain 2,500 American troops in the country instead of executing a full withdrawal. General Milley indicated that he had indeed supported that position until President Biden announced his withdrawal plan. “I rendered my opinions, and it was a fulsome debate on all of that,” General Milley testified. “And once decisions are made, then I am expected to execute lawful order[s].”67
Ranking member Rogers then posed similar questions to General McKenzie, asking him to characterize the advice given by the commander of US-led coalition forces in Afghanistan, General Austin Miller. “The advice, his view and my view, were essentially the same view,” Miller said. “My view was we needed to maintain about 2,500 and that we also needed to work with our coalition partners who had about 6,000 troops in there, NATO and other core countries that would remain there.” Rogers then asked whether General McKenzie’s “professional military opinion” changed over the course of the spring. “It did not,” McKenzie said.68
The surfacing of the generals’ disagreement with the president’s decision was balanced by the satisfaction they expressed with the deliberative process that led to the outcome, blunting the degree to which their testimony could be framed as advantaging one partisan narrative or another in a highly charged issue. When asked whether he felt his recommendations had been adequately considered, McKenzie responded affirmatively. “They were debated fully,” McKenzie said. “I felt that my opinion was heard with great thoroughness by the president.”69 General Milley acknowledged that his advice was that of the uniformed military, and recognized the narrower scope of his authority relative to the civilians who ultimately make broader national security policy decisions. “I would tell you this administration did—and I was part of it, along with the Joint Chiefs—a very rigorous process,” Milley said. “We in the military, in the uniformed military, we look at the cost, at the risk to force, the benefit, et cetera, in a narrow-focused view. Other decisionmakers have a much wider angle.” 70
Members of the HASC who sought to bolster the president’s decision turned to the Defense Department’s politically appointed civilian leadership—rather than the uniformed military—to make the administration’s case, a choice that reflected a normatively desirable effort to separate the administration’s policies from those officers charged with executing them. Democrats on the HASC asked Secretary of Defense Austin questions that sought to draw out support for President Biden’s policies and shift blame for the withdrawal’s outcome onto Biden’s predecessor, President Donald Trump. For example, Representative Jackie Speier (D-CA) asked Secretary Austin whether the previous administration had developed withdrawal plans. “There was no handoff to me of any plans for a withdrawal,” Austin said. Rep. Speier clarified: “So then-President Trump calls for a total withdrawal by May 1, 2021, and no plans had been made during his administration for withdrawal.” In response, Secretary Austin stated that commanders at the theater and ground level had been planning for such a contingency, but added that such plans were not transmitted at the level of the department’s civilian leadership: “[I]n terms of administration to administration, Secretary to Secretary, there was no handoff to me,” Austin recalled.71
In other cases, some members of the president’s party took a more confrontational stance toward the witnesses in ways that do not strictly align with the incentives imposed by Washington’s increasingly polarized environment. Representative Seth Moulton (D-MA), a combat veteran, questioned the Defense Department’s delay in processing special immigrant visas for Afghan citizens who had helped the American military effort. Moulton’s implication was that the department had done so under pressure from Afghanistan’s then-president, Ashraf Ghani. Moulton then questioned General McKenzie’s delay in mobilizing for an evacuation as the Taliban adversary gained ground:
Moulton: You have said repeatedly that you personally believe the Afghan government would fall if we didn’t maintain a certain number of troops in country. So why didn’t you plan for an evacuation and leave enough troops on the ground to conduct it?
McKenzie: So let’s be very clear. The evacuation must be ordered by the Department of State. The drawdown of US forces was ordered by the President in April and completed in July. The noncombatant evacuation operation is a separate mission, and it was not completely under the control of the Department—
Moulton: So you are going to fall back on the bureaucracy, the divide between DOD and State—
McKenzie: Well, representative, I am going to fall back . . . on the orders that I received, representative.72
Similarly, both Democratic and Republican members of the committee questioned the advisability of having closed Bagram Airfield in July 2023, which left military leaders to rely on Hamid Karzai International Airport (HKIA) in Kabul to facilitate an evacuation. “The center of gravity of a NEO [noncombatant evacuation operation] was always going to be HKIA,” General Milley testified. “The security issues clearly are different at HKIA than they are at Bagram, but Bagram was really not a feasible option given numbers of troops, distance, and the security requirements.”73
As the exchanges above demonstrate, members of the HASC from both parties directed their questions toward witnesses in ways that reflected normatively desirable elements of the civil-military dialogue. Democratic members reserved some of the most politically charged questions about the administration’s policy for the politically appointed secretary of defense, thereby avoiding dragging the military into partisan waters. Members of both parties directed operational questions toward military officers in ways that did not strictly conform to the political incentives associated with an increasingly polarized political environment. Committee members did so even when attempting to surface disagreements between the military judgments these officers recommended to the president and the different course of action he took against that advice.
At the same time, the hearing evinced the kind of bitter exchange that threatens to become more frequent as partisan polarization becomes more extreme. The sharpest exchange took place under questioning from Representative Matt Gaetz, Republican of Florida, who used the hearing to launch into a hostile diatribe against the uniformed officers at the committee. “You seem to be very happy failing up over there, but if we didn’t have a president that was so addled, you all would be fired because that is what you deserve,” Gaetz said. “You have let down the people who wear the uniform in my district and all around this country. And you are far more interested in what your perception is and how people think about you and insider Washington books than you care about winning.” 74 Derisive personal attacks against senior military officers were once unthinkable, but—as this exchange shows—increased partisan polarization and deepening divisions within the parties themselves have contributed to eroding confidence in military leadership, along partisan lines.75
Increased partisan polarization can also hamper the ability of the country to draw lessons from previous mistakes—a point that HASC Chair Smith seemed to raise later in the hearing.
Increased partisan polarization can also hamper the ability of the country to draw lessons from previous mistakes—a point that HASC Chair Smith seemed to raise later in the hearing.76 “While we are ripping apart these three gentlemen here, I want to remind everybody that the decision the president made was to stop fighting a war that, after 20 years, it was proven we could not win,” Smith said. “There was no easy way to do that.”77 Congress would subsequently create an independent Afghanistan War Commission to conduct a comprehensive review of the two-decade-long conflict, in part to insulate its conclusions from the creeping partisan polarization that has pervaded Congress.78
Implications and Future Research
Overall, we find that Congress has demonstrated a surprising consistency over time in the share of civilian, military, and nongovernment witnesses it calls to testify. Broadly speaking, the share of civilian and military witnesses who appear before the HASC has remained remarkably stable over time, even when accounting for increased occurrences of divided government and rising partisan polarization within Congress. In some cases, deviations from this general trend in HASC witness rosters correspond to larger structural and organizational shifts in the international and domestic political environment—a change reflected in the higher share of military witnesses relative to civilian government officials between 2001 and 2006, which corresponds with the early stages of the wars in Iraq and Afghanistan.
While our findings are largely descriptive, this article offers important avenues for future research on Congress’s role in shaping defense policy. For instance, our findings have implications for the kinds of time horizons Congress can be expected to prioritize when intervening in defense policy debates. HASC appearances by combatant commanders have increased over the last several decades relative to members of the Joint Chiefs of Staff, a development that reflects both the growth in number of combatant commands and their elevation in authority under the 1986 Goldwater-Nichols Act. Increased input from combatant commanders could create a near-term bias, because combatant commanders operate under the demands of the near-term environment while service chiefs focus on long-term development of the force. Future work might examine whether and how changes in the composition of HASC witnesses have changed the content of combatant posture statements, shifted the allocation of defense resources away from the services and toward combatant commanders, or produced other changes in defense policy that emphasize near-term crises at the expense of long-term planning.
Future work might also expand the scope of the data gathered to compare differences in the composition of witnesses called before the HASC and its Senate counterpart. Additional studies could extend our temporal scope to include all Congresses in the period we examined. Additionally, our qualitative case study emphasizes the potential to employ text analysis to conduct systematic assessment of the content associated with various witnesses (for example, the kinds of questions witnesses are asked and how they answer). Researchers could investigate, for example, whether different types of military officers offer different time horizons for the threats they confront, or whether they are asked for personal military judgments more often by members of the party opposed to whoever sits in the White House. Other studies might compare how civilian government officials and uniformed military officers respond to comparable questions.
Researchers might also investigate the degree to which members of Congress direct particular questions to specific types of officials, in part to evaluate whether matters of policy are directed towards politically appointed civilians as opposed to uniformed officers.
Finally, our study offers important implications for Congress’s ability to exercise effective civilian control over the United States’ armed forces. We find that Congress has consistently turned to civilian government officials to testify on defense matters across presidential administrations, a pattern that delivers a reassuring degree of stability to civil-military relations, and that appropriately concentrates debates over national security policy among civilian policymakers. Congress appears to have resisted the temptation to supplant civilian expertise and authority and substitute testimony from uniformed military officers, even though those witnesses sometimes command greater attention and public confidence. The fact that military officers are no more likely to appear before the HASC under periods of divided government should reassure those worried that politicians are seeking to exaggerate or exploit divisions between the uniformed military and civilian authorities for electoral or partisan gain.
At the same time, the persistence of these rates of participation by civilian and military witnesses in the face of growing partisan polarization increases the risk that uniformed officers will find themselves dragged into partisan debates. Even if the frequency of testimony by military officers has not changed, congressional hearings have themselves become politically charged settings. The enduring presence of military officers at hearing tables raises the risk that these uniformed personnel could be lured into partisan waters during even routine testimony or mistakenly perceived as supporting partisan positions when simply following lawful orders of elected civilians.79
We find that Congress has consistently turned to civilian government officials to testify on defense matters across presidential administrations, a pattern that delivers a reassuring degree of stability to civil-military relations, and that appropriately concentrates debates over national security policy among civilian policymakers.
To counter these risks, political appointees must be willing to step in to take questions that will prevent military officers from being caught in partisan crossfire. This measure should enable senior military officers to deliver candid assessments without compromising civil-military relations norms. Scholar-practitioner Alice Hunt Friend, a former civilian within the Defense Department, argues that civilian defense officials have erroneously adopted an apolitical approach to their roles akin to the professional norms ensconced within the armed services. She further warns that while appointees should not engage in partisan politics, they nonetheless cannot abjure the politics of governing, which consist of prioritizing policies and directing resources toward particular programs.80 By embracing the rough and tumble of governing politics, politically appointed civilians in the Defense Department can help insulate their military counterparts from partisan politics when called to testify.
Jessica D. Blankshain is an associate professor of national security affairs at the US Naval War College. Her research interests include civil-military relations, bureaucratic politics, and organizational economics. Her work has appeared in the American Political Science Review, and, with Nikolas Gvosdev and David Cooper, she is coauthor of Decision-Making in American Foreign Policy: Translating Theory into Practice (Cambridge University Press, 2019).
Theo Milonopoulos is an assistant professor of national security affairs at the US Naval War College. His research interests include foreign policy decision-making, civil-military relations, and the national security implications of emerging technologies. His work has appeared in the Journal of Conflict Resolution and has been supported through fellowships at the University of Pennsylvania’s Perry World House and the Clements Center for National Security at the University of Texas at Austin.
Derek S. Reveron is professor and chair of the National Security Affairs Department at the US Naval War College. He is a faculty affiliate at the Belfer Center for Science and International Affairs at the Harvard Kennedy School. He served 33 years in the Navy Reserves leading units in support of operations in the Middle East, Europe, Asia, and Latin America, and was a special advisor in Afghanistan. With John Savage, he is coauthor of, most recently, Security in the Cyber Age: An Introduction to Policy and Technology (Cambridge University Press, 2024).
Acknowledgments: The authors are grateful for research assistance from Justin Bowling, Kane Magnuson, and Yannis Normand (supported by Harvard Extension School) and Gregory Langston and Ken Sandler (from the Naval War College). Our colleagues in the National Security Affairs Department continue to inspire new thinking on foreign policy analysis and international security and truly live up to the ideal that the college is the Navy’s and the nation’s home of thought.
The views expressed here are those of the authors and do not necessarily represent the views, policies, or positions of the US Department of Defense or its components, to include the Department of the Navy or the US Naval War College.
Image: U.S. Coast Guard District 5 photo by Petty Officer 2nd Class Patrick Kelley