Dr Chris Dolan is a Professor of Political Science and Director of International Relations at Lebanon Valley College. He has been awarded the prestigious Fulbright Scholarship.


For a chief executive, leader, or top advisor entrusted with formulating and implementing foreign policy, the selection of an effective Chief of Staff (COS) is paramount. With the acceleration of globalization, the development of a multipolar world with competing power centers, and economic interdependence, governing and leading foreign policy in ways that promote stability and prosperity has become an even more challenging and complex endeavor. This article examines the evolving foreign policy roles played by the COS in coordinating foreign policy staff and advising the chief executive in international affairs. It highlights the different ways in which White House Chiefs of Staff have served the foreign policy agendas of American presidents. The article moves beyond the White House to describe the COS in select government departments and agencies with responsibility for security, diplomacy, and foreign assistance. It concludes by establishing general parallels beyond government and suggests that an effective COS is among the most important resources for a chief executive entrusted with leading foreign policy.

The Chief of Staff (COS) is the principal advisor and staff manager who interacts the most with the chief executive and other officials on foreign policy matters and international affairs. The COS plans meetings between the chief executive and national security, intelligence, and diplomatic officials, manages foreign policy staff, and oversees the foreign policy bureaucracy. The COS is also the gatekeeper of the foreign policymaking process and is often the last person in the room when the chief executive makes key foreign policy decisions. As this article will demonstrate, COS’s are the most important and consequential official in government entrusted with advising and coordinating the chief executive’s foreign policy agenda.

In particular, the White House COS is the most valuable unelected government official not confirmed by the U.S. Senate. The COS is entrusted with channeling advice and information from foreign policy staff in the White House Office (WHO) and government bureaucracy to the president on issues in U.S. national security, intelligence, diplomacy, and the economy. The COS develops the president’s daily schedule and coordinates deputy chiefs of staff, senior political advisors, the Counselor to the President, the vice-presidential COS and the VP’s national security advisor, the press secretary, directors of Political, Communications, and Legislative Affairs, and the Office of Management and Budget (OMB). The relationship between the COS and the president’s National Security Advisor (NSA), deputy NSA’s and National Security Council staff, Secretaries of State and Defense, and Director of National Intelligence are consequential to the chief executive’s foreign policy agenda. Other influencers include the National Economic Council (NEC), the U.S. Trade Representative (USTR), and the Council of Economic Advisors (CEA).

The COS informs the president of international crises and, as the gatekeeper, has the power to decide who is in the room to shape national security issues and international economic priorities. Two of the most effective COS were Republican James A. Baker III and Democrat Leon Panetta, who deftly balanced their roles as managers of the WHO and as trusted foreign policy advisors. While this article will examine several advisory modes, the COS was seriously downgraded during the Trump Administration because of strained personal relations between the president and his four COS’s and the development of an independent and rival powerbase in the White House led by former President Trump’s son-in-law, Jared Kushner. President Joe Biden’s selection of Ron Klain as COS sends an important signal that his White House will lean heavily on stability, competence, and experience.

The COS is the mediator between the chief executive or top official and that leader’s team of foreign affairs advisors. To be effective, the COS should operate, as much as possible, in the background and in a low-key fashion to broker disagreements, manage access, and coordinate information. Put simply, the COS is a primary adviser and confidant who serves as a sounding board and deflector so the chief executive can function and make foreign policy decisions. Sound foreign policymaking also depends on the ability of the COS to organize an executive system staffed with competent and experienced personnel.

This article is organized into four sections. The first provides a general overview of the COS as both a foreign policy advisor to the chief executive and as manager of the foreign policymaking process. The second examines the dual roles played by White House Chiefs of Staff in advising and managing the foreign policy agendas of American presidents. The third digs deeper into the U.S. foreign policy bureaucracy by describing the roles of COS’s who serve U.S. Secretaries of State and Defense and the COS at the U.S. Agency for International Development. The fourth concludes that the foreign policy roles of the COS in government have lessons for the COS in the private sector.


Dual Roles: COS as Manager and Advisor

The search for an effective COS involves finding an experienced and skillful professional who can strike an appropriate balance between managing the foreign policy staff and advising the chief executive. As a manager, the COS coordinates the schedule and organizes the COS office, deputies, and staff to suit the needs of the executive’s management style. The COS scrutinizes and hires experienced staff members, smooths the flow of information, and integrates advice. The COS knows how and when to involve the executive in foreign policymaking process, mediates competing interests, and serves as an honest broker in making foreign policy decisions.

As an advisor, the COS serves as a gatekeeper who ensures other top foreign policy advisors have access at the appropriate time, protects and advocates the executive’s foreign policy agenda, negotiates with key legislative committees, ensures bureaucratic implementation of foreign policy decisions, and offers their knowledge on the security, diplomatic, and economic dimensions of foreign policy. However, the COS should be mindful of executive reputation and the trappings of office. To function effectively as both foreign policy advisor and manager, the COS must contend with political limitations and bureaucratic constraints on the chief executive’s power.


Political Limitations

An effective COS knows that chief executives are also confronted with political limitations on their power in foreign policy and international affairs. Since time is of the essence, they need to act quickly and responsibly to keep the chief executive involved in foreign policy decision-making. Given that other top-level advisors may have competing interests, an effective COS will serve as an honest broker and mediator to manage the games foreign policy advisors play.

Other political forces exert limit the exercise of executive power and, by consequence, can limit the ability of the COS in their advisory roles. In a system of checks and balances, legislatures share foreign policymaking functions with chief executives, especially over defense and international affairs budgets. The COS must devote considerable time and effort to move the chief executive’s preferred foreign policy initiatives through the legislature. In addition, democratic systems and societies have political parties, powerful interest groups, and social movements that the COS must work with to promote the chief executive’s foreign policy agenda. The COS knows that the same paradox of power that inhibits executive action in domestic policy can also constrain the chief executive in foreign policy.


Bureaucratic Constraints

The COS also wrestles with large and deeply entrenched bureaucratic organizations in foreign policy. Agencies and departments have cultures, interests, and tasks that could be at odds with the foreign policy preferences and behavior of the executive. For example, in the U.S., the COS to the U.S. Secretary of State must be sensitive to and aware of the unique culture of the State Department, which values autonomy, freethinking, and creativity among its diplomatic personnel. According to David Wade, who was COS to Secretary of State John Kerry, “the State Department is like an iceberg. The view from the outside is deceiving. It is a huge managerial and organizational challenge different from any other.”[1]

Since the COS is reliant on the foreign policy bureaucracy for information, they must ensure communications are clear and turf battles are mitigated. National security and international economic organizations determine not only the quantity of information available to the COS but also the quality and range of foreign policy options. Furthermore, bureaucrats have conflicting relationships with legislators and their staffs who fund international affairs programs. In the next section, this article examines in greater detail the ways in which White House COS’s served the president’s foreign policy interests and administered the foreign policymaking process.


The White House Chief of Staff and Foreign Policy

Like other chief executives around the world, U.S. presidents have unique worldviews and perspectives that shape their approach to foreign policy. These include background, personality traits, and managerial styles that determine how they govern foreign policy. In organizing staff and providing advice, the COS must take these into consideration. As this section will demonstrate, presidents since Richard Nixon have employed very different approaches to managing the White House with varying degrees of success.


Haldeman’s Rigidity and Regan’s Isolation

Some American presidents have preferred to organize the White House with formal and hierarchical patterns. This was the case with President Richard Nixon who often circumvented his Cabinet to concentrate power in the White House. COS HR Bob Haldeman created a staffing structure that allowed Nixon to work with National Security Advisor Henry Kissinger on ending the Vietnam War and opening diplomatic negotiations with China. Haldeman also served as a gatekeeper and referee between Kissinger who coordinated foreign policy and John Erlichman who was given responsibility for domestic policy.

Haldeman adapted to Nixon’s inflexible, aggressive, and power-seeking style. He viewed Nixon, who often isolated himself in a private study in the Old Executive Office Building, as needing “to be protected from himself.” Haldeman described Nixon as issuing “vindictive orders” designed to “try to defeat his opponents.”[2] Instead of deflecting them, Haldeman fed Nixon’s worst instincts. It is no surprise Haldeman was willing to execute Nixon’s Watergate cover-up and is the only COS to serve time in prison.

President Ronald Reagan’s second COS, Donald Regan, also developed a very rigid White House advisory system. Such a system may have suited Regan’s preference for a command-style approach, but it did not reflect the president’s style, which was more flexible and open. Regan imposed a structure that shielded the president from countervailing information that would have protected him. With Reagan isolated, his administration became consumed by the Iran-Contra scandal, which almost took down his presidency. The Reagan White House became so paralyzed by Iran-Contra that the beleaguered president was forced to negotiate from a weakened position with Soviet leader Mikhail Gorbachev on the Intermediate Nuclear Forces treaty.


Carter’s Carefree Approach and McLarty’s Inexperience

At first, President Jimmy Carter decided not to have a COS, which meant there was no political enforcer working on his behalf. The White House staff was given leeway, often speaking on their own and without retribution. It often fell on Carter himself to mediate among his closest advisors. While this allowed Carter to prioritize his foreign policy initiatives, such as the Israel-Egypt peace negotiations and human rights, the absence of a structured foreign policy approach made it difficult to speak with one voice.

By the time Hamilton Jordan became Carter’s COS, foreign policy advisors were clashing with one another.  Without an effective gatekeeper, National Security Advisor Zbigniew Brzezinski and Secretary of State Cyrus Vance competed for influence and impeded the president’s outreach to Congress to accomplish foreign policy goals. For example, Carter’s negotiations with the U.S. Senate on Panamanian sovereignty over the Panama Canal, a process that began under Nixon, were politically haphazard and disorganized leading to Democratic losses in the 1978 midterm elections. Also, clashes over the U.S. response to the Hostage Crisis in Iran contributed to Carter’s defeat in 1980.

President Bill Clinton’s first COS, Thomas “Mack” McLarty, implemented an open system in which advisors from National Security Advisor Sandy Berger to political advisors like George Stephanopoulos had equal access to the president. Clinton ran his foreign policy operation the same way he ran his campaign, with an undisciplined and informal style. During the 1992 transition, while Clinton concentrated on his cabinet picks, he did not select McLarty until a month after he was elected.

However, Clinton’s White House staff, including COS McLarty, had little Washington political experience, making outreach to Congress on foreign policy priorities difficult and challenging. The freewheeling approach allowed advisors to pursue their own agendas to the detriment of the president’s foreign policy goals. Clinton was often ill-prepared to deal with major international challenges, such as in October 1993 when U.S. troops were killed in the humanitarian mission in Somalia, during the failed attempt to remove Raul Cedras in Haiti, and in April 1994 when his administration failed to respond to the genocide in Rwanda. While McLarty presided over the White House during the passage of the North American Free Trade Agreement, Clinton alienated the Democratic Party’s working-class base. This along with the failure to pass health care reform contributed to Democratic losses in the 1994 elections.


Gold Standards: James A. Baker III and Leon Panetta

Other COS combine relatively hierarchical structures with a president who has a more flexible management style to ensure multiple and competing information is reflected in the foreign policymaking process. In such a system, the COS maximizes their role as gatekeeper. President Ronald Reagan’s first COS, James A. Baker III, developed a disciplined advisory system that emphasized multiple sources of information and ensured the president heard from different advisors.

Baker was aware of Reagan’s optimism and agreeability. While Baker’s COS system worked and Reagan’s foreign policy priorities were advanced, namely his defense spending program and tax cuts, his role as gatekeeper was unbearable. Baker (quoted in Whipple 2018) described his role as someone who “walks around with a target on his back and on his front.” Baker’s staffing system was flexible and agile.

Baker was a very effective delegator. He would allocate key responsibilities to Deputy COS Michael Deaver and Counselor to the President Edwin Meese who had closer relationships with both the president and First Lady Nancy Reagan. Deaver devoted much of his time overseeing the First Lady’s schedule, the military office, and the East Wing of the White House (Cohen and Walcott 2020). Baker set such a high standard in managing White House staff and advising the president that his predecessors in both Republican and Democratic administrations are measured by his flexible yet disciplined COS system.

Clinton’s second COS, Leon Panetta, developed a more disciplined COS system that, while at odds with the president’s open management style, helped mitigate its negative effects. Panetta, who was Director of the Office of Management and Budget and a former U.S. Representative, held daily staff meetings, developed organizational charts, and planned the president’s schedule months in advance. This allowed Panetta to oversee what everyone was doing in foreign policy, manage countervailing information from different advisors, and more effectively control access to the president. As a result, Clinton made some notable foreign policy accomplishments, such as negotiations for the withdrawal of Russian troops from Estonia and Latvia, developing the World Trade Organization (WTO), U.S. containment of the Mexican Peso Crisis, NATO intervention in Bosnia, and conclusion of the Dayton Peace Accords.


Serving Needs and Offsetting Vulnerabilities: Andrew Card as COS

Andrew Card, who served for more than five years as President George W. Bush’s first COS, coordinated the White House during some of the most consequential and controversial foreign policy challenges and decisions. Card informed Bush of the September 11th terrorist attacks, led White House counterterrorism policy, including passage of the PATRIOT Act, the invasions of Afghanistan and Iraq, the Iraqi insurgency, NATO expansion, the color revolutions in Ukraine and Georgia, and the rise of China. Card had considerable political experience, having served as White House deputy COS and Transportation Secretary under George HW Bush and as a state representative in the Massachusetts legislature. Card viewed his foreign policy role as compensatory to the president and adapted every aspect of the White House staff to the president’s personality and world view. Card stated, “the organizational chart should reflect the needs the president has rather than the bureaucracy that he’s inherited” as well as to impose discipline on the White House in ways that enabled Bush to meet his foreign policy objectives.[3]

Card ‘s role as COS was to offset structural and personal vulnerabilities in Bush’s advisory system. However, he would often be frustrated with managing more high-profile political advisors like Karl Rove and Karen Hughes who routinely appeared on talk shows. This led many to think Card, Rove, and Hughes constituted a “Troika” of advisors, an arrangement Card strongly objected to because it undermined his managerial and advisory roles (Cohen and Walcott 2020).


Balancing Continuity with Change: Josh Bolten Steps In

Card’s successor, Joshua Bolten, maintained relative continuity in the structure of Card’s advisory process. Before serving as Bush’s second COS, Bolten was Bush’s OMB Director, deputy COS for Policy, and was an advisor on Bush’s 2000 presidential campaign. As COS, Bolten was immediately confronted with the task of overseeing the president’s “surge” strategy in Iraq. This meant his job would intersect with National Security Advisor Stephen Hadley. This was a delicate balancing act, in which Bolten ensured that the president was not cut off from the foreign policymaking process and offered his advice on how to interpret different national security information from Hadley and Secretary of Defense Donald Rumsfeld. Bolten also kept the White House in close communication with the Pentagon and General David Petraeus in Iraq.

Bolten had to manage significant changes to the Cabinet. One of his first duties was dealing with the so-called “revolt of the generals” who were protesting the Iraq war strategy. Bush, who was reluctant to make top-level staff changes, was urged to replace Rumsfeld and alter the Iraq War strategy. Bolten quickly pivoted to his advisory role by working with Secretary of State Condoleezza Rice and Hadley to bypass Vice-President Dick Cheney, a vociferous defender of Rumsfeld. Bush was also coming under increased public pressure to end a war he promised would be over soon after the invasion. Interestingly, after Democrats assumed control of Congress in 2006, Bush replaced Rumsfeld with Robert Gates. Bolten also downgraded Rove’s role whose fame impeded the White House’s ability to shift course.


Rahm Emanuel as Political Enforcer and Denis McDonagh as Skilled Operator

While President Barack Obama had four COS in eight years, Rahm Emanuel and Denis McDonough stand out. Rahm Emanuel was Obama’s political enforcer, often deflecting negative attention away from the president. Emanuel’s managerial process was to get early policy wins by following through on campaign promises, namely the massive fiscal response to the global financial crisis, the Great Recession, and the U.S. military withdrawal from Iraq.  He played a very significant role in Obama’s counterterrorism strategy by directing his staff to ensure close communications on the use of armed drone strikes.[4]

Denis McDonough is one of the few COS who had significant foreign policy experience. Previously, McDonough was COS to the National Security Council staff and served as deputy national security advisor. Prior to the Obama Administration, he was an Obama campaign foreign policy advisor and senior foreign policy advisor to former U.S. Senator Tom Daschle.

As COS, McDonough organized a staffing system that concentrated foreign policy in the West Wing and away from the cabinet departments, especially the more difficult to control departments of state and defense. While McDonough ensured that Obama was always consulted, it worsened relations with top officials in the cabinet. In August 2013, McDonagh played a significant role when Obama considered launching airstrikes in Syria in response to Bashar al-Assad’s use of chemical weapons. McDonough, who shared Obama’s non-interventionist instincts and did not want his boss to repeat the mistakes of the NATO-led intervention in Libya in 2011, helped push Obama to avoid military intervention.


Four Chiefs in Four Years and Family Matters: Instability and Chaos in the Trump White House

President Trump’s four COS in four years were forced to contend with a personality that was openly confrontational with both Democrats and Republicans, politically polarizing, and highly resistant to information or persuasion from outside his inner circle. Suspicious of experts, Trump staffed the White House with those he deemed personally loyal to him, namely his daughter Ivanka Trump and son-in-law Jared Kushner, and close personal confidants such as Steve Bannon, Hope Hicks, Stephen Miller, and Peter Navarro. COS Reince Priebus, John Kelly, Mick Mulvaney, and Mark Meadows were left to contend with a White House that enabled the president’s impulses and inhibited his ability to influence foreign affairs.

Priebus and Kelly struggled to contend with White House clashes over the Mueller investigation on Russian interference in the 2016 presidential election. Priebus tried holding regular senior staff meetings and channeling information through himself.  However, an orderly system never emerged. Priebus, who was Republican National Committee Chair, was beleaguered and struggled to manage the undisciplined Trump. Retired U.S. Marine Corps General and former Secretary of Homeland Security John Kelly imposed a much more disciplined structure on the White House staff with tighter organization that limited access to the president. However, like Priebus, Kelly struggled to manage Trump’s freewheeling style and focused on preventing the volatile president from mismanaging foreign policy. Consequently, Republicans lost control of the House of Representatives in 2018.

Mick Mulvaney and Mark Meadows did not fare any better. Mulvaney, who held the title of Acting COS, opted against advising the president on foreign policy matters and simply permitted the unpredictable “Trump to be Trump.” Mulvaney was sidelined by Kushner who allowed unfettered access to family members and those who enabled the president’s worst instincts. Trump soon became embroiled in the House impeachment inquiry into his use of a shadow foreign policy network run by former New York Mayor Rudy Giuliani. Although he escaped removal from office by the Senate, that inquiry found Trump threatened to withhold U.S. security assistance to Ukraine to pressure President Volodymyr Zelensky into investigating Joe Biden. During the COVID-19 pandemic, Mulvaney and the White House staff failed to coordinate with the coronavirus task force on building testing capacity and left state governors to compete for life-saving protective equipment and medical personnel on their own to contend with rising hospitalizations, infections, and deaths.

Mulvaney’s successor, U.S. Representative Mark Meadows, also struggled to impose discipline on the White House. The more hands-on Meadows looked at his role as a balancing act between advising his boss and maintaining relations with Trump’s family members. The problem for Meadows was that the Trump White House was already overwhelmed by the pandemic and the collapsing economy. According to Whipple, “One of the principal reasons we are in this mess is because Trump has never had a chief of staff who will tell him hard truths…”[5]  Trump’s controversial presidency, the tainted 2016 election, multiple investigations and two impeachments, the bungled response to COVID-19, and the economic recession led to his defeat in 2020. Since managing the leader is just as important as managing the office, COS’s cannot do their jobs effectively if they hampered and undermined by the chief executive.


Managing Multiple Crises: Ron Klain as Biden’s COS

President Joe Biden’s selection of Ron Klain was based on his preference for someone who has both long experience in Washington politics and enjoys a close working relationship with the new president. Klain was point person on the 2009 Recovery Act and helped lead the U.S. response to contain the Ebola outbreak in 2014. Klain will certainly have his hands full as he is tasked with overseeing the White House response to the COVID-19 pandemic and the establishment of a national vaccination plan as well as with shepherding a massive coronavirus relief package through Congress. Klain will also be responsible for coordinating U.S. reentry into the World Health Organization (WHO) and the Paris Climate Accords.

However, Biden will be challenged with repairing America’s damaged alliances, especially NATO. He must also respond to Russia for interfering in U.S. elections and its devastating cyberattacks against U.S. government and private networks in 2020. He will also seek renewal of a New Start nuclear arms treaty with President Vladimir Putin and wrestle with China’s rising global power. Biden’s success in foreign policy will be depend on Klain’s relationship with National Security Advisor Jake Sullivan and Secretary of State Antony Blinken and be determined by a disciplined staff that can engage with Congress and the foreign policy bureaucracy. The next section turns to the roles played by the COS in key bureaucratic departments and agencies.


The COS in the Foreign Policy Bureaucracy

This article highlights the foreign policy roles played by the COS. However, other some top-level officials in the foreign policy bureaucracy employ their own chiefs of staff to discharge responsibilities. In the U.S., these include senior administrative officials at the Cabinet and sub-Cabinet levels who advise the president and administer national security and foreign policy initiatives.


The COS to the Secretary of State and USAID

The most consequential and important COS position in the foreign policy bureaucracy is to the Secretary of State. The COS is senior advisor to the Secretary of State and manager of top and mid-level foreign affairs staff, including those in the U.S. Foreign Service as well as the principal deputy secretary and deputy secretary for foreign assistance programs. The COS also works with the counselor, the director of policy and planning, and undersecretaries of state, regional assistant secretaries of state, the chief economist, U.S. Ambassadors and Special Envoys, and directors of diplomatic initiatives and policy programs.

Since 2002, there have been six COS to Secretaries of State. COS Lawrence Wilkerson served Secretary of State Colin Powell and oversaw some of the most critical and controversial national security matters. These included the use of faulty CIA intelligence to aid Powell in his controversial 2003 United Nations Security Council presentation, maladroit U.S. stabilization efforts in Iraq, and torture and abuse at Abu Ghraib prison. Brian Gunderson served as a low-key COS to Secretary of State Condoleezza Rice, focusing more on outreach to the State Department staff and Congress.

Cheryl Mills was both COS and Counselor to Secretary Hillary Clinton. Mills supervised food security and foreign assistance initiatives in Haiti after the 2010 earthquake and advised Clinton during the Arab Spring uprisings and the U.S. role in the 2011 NATO mission that toppled Muammar Gadhafi in Libya. She was also a liaison with the Clinton Foundation, which raised ethics questions and conflicts of interest with the State Department. Mills was even questioned by the FBI during the congressional investigation of whether attorney-client privilege could be applied to Clinton’s private email server.

David Wade served as COS to Clinton’s successor, Secretary John Kerry. Wade was low-key in his COS role, focusing on day-to-day operations and bringing calm and stability to a State Department that was involved in nuclear negotiations with Iran in the Joint Comprehensive Plan of Action, one of the Obama Administration’s signature diplomatic achievements. The State Department was also confronted with challenges that tested American power, especially the U.S. response to Bashar al-Assad’s use of chemical weapons in Syria, Russia’s seizure of Crimea in 2014, and the rise of the Islamic State.

Jonathan Finer succeeded Wade as Kerry’s COS and served as Director of Policy Planning simultaneously. Finer brough considerable foreign policy experience to the position as Vice-President Joe Biden’s foreign policy speech writer, staff member for the National Security Advisor, and as foreign affairs correspondent with the Washington Post.  Finer was a close adviser to Kerry and assisted him with multilateral negotiations in the Paris Climate Accords and the Trans-Pacific Partnership.

Secretary of State Rex Tillerson named Margaret Peterlin as COS. Previously, Peterlin served as communications officer in the U.S. Navy and on Republican House Majority Leader Dick Armey’s staff, as national security advisor to House Speaker Dennis Hastert, and in the Department of Homeland Security. As Tillerson’s COS, she functioned as a gatekeeper, limiting media access to the State Department and Tillerson himself. After Tillerson was fired in March 2018, Peterlin resigned and Secretary Mike Pompeo did not name a COS. Moreover, under both Tillerson and Pompeo, State Department morale plummeted in response to budget cuts to diplomatic staff and the foreign service and because of Trump’s pressure campaign against U.S. diplomats in Ukraine. Key ambassadorships were also left unfilled in several allied nation-states, including South Korea, Germany, and Egypt.

The U.S. Agency for International Development (USAID) has its own COS who manages staff and advises the Administrator on foreign assistance programs. While USAID is an independent agency, the USAID Administrator works under the Secretary of State. This design ensures that the State Department focuses on diplomatic relations and USAID implements foreign assistance programs. During the Trump Administration, Dr. Bill Steiger was USAID COS who coordinated U.S. development assistance programs in the global effort to contain the COVID-19 pandemic.  Other COS play pivotal roles in agencies that implement foreign assistance programs, including the Millennium Challenge Corporation and the Overseas Private Investment Corporation.


The COS to the Secretary of Defense

Like the Department of State, the Pentagon COS serves in somewhat similar capacities. As COS to Secretary of Defense Ashton Carter, Eric Rosenbach oversaw several defense initiatives, namely cyber defense, Russian aggression in Donbas and the annexation of Crimea, the Syrian Civil War, the military campaign against the Islamic State, and North Korean missile testing. Rosenbach also helped establish the Defense Innovation Unit and the Defense Digital Service. Previously, Rosenbach was an Army intelligence officer, deputy COS, and Assistant Secretary of Defense for Homeland Defense and Global Security where he was the primary architect of cyber defense policy.

Retired Rear Admiral Kevin Sweeney was named Secretary of Defense James Mattis’s Pentagon COS. Sweeney devoted much of his time to working closely with Mattis and Special Envoy Brett McGurk in coordinating international combat operations in Syria and Iraq against the Islamic State.  Sweeney announced his departure in January 2019 following Mattis’s resignation in response to Trump’s withdrawal of U.S. troops from Syria.

Combat veteran and former Army intelligence officer Eric Chewning was named by Secretary of Defense Mark Esper as Pentagon COS. Chewning focused primarily on reforming staffing operations in Esper’s office. He contended with the legality of Trump’s White House move to hold up security assistance to Ukraine, which prompted the president’s House impeachment.

Jen Stewart, who replaced Chewning as COS in January 2020, brought considerable expertise to his office, especially on developing foreign policy strategy against China and Russia and in cybersecurity. However, devastating Russian cyberattacks against the U.S. took place while Stewart was Pentagon COS. After Trump’s loss in the 2020 presidential election and his firing of Esper, Stewart resigned and was replaced by NSC counterterrorism staff director Kashyap Patel who was Pentagon COS for Acting Secretary of Defense Christopher Miller during Trump’s remaining days in office.



Since HR Bob Haldeman, the COS has played an increasingly greater role in foreign policy and international affairs. Given the vast foreign policy powers of the presidency, the president has fewer institutional constraints than in domestic policy. This means the foreign policy bureaucracy has significant autonomy to either carry out or resist the president’s foreign policy agenda.  Moreover, presidents often find themselves stymied in the domestic arena and turn to foreign affairs to secure big accomplishments they believe will pay them political dividends.

In many ways, COS’s in the private sector should look at the experiences of COS’s in government to learn how best to maximize opportunities, navigate hindrances, and avoid the pitfalls and pressures of leading large and complex organizations. A COS who manages and advises a corporate CEO is like a COS in government. A corporate COS ensures that the CEO can maximize time, manages information flow, adjusts operations to the leader’s style, and implements executive decisions. The executive should select a COS who can lead day-to-day office operations, maintain morale among the staff and in the chief executive, and manage access and provide sound advice.  This includes integrating staff who otherwise might be divided, linking the executive with the organization, and serving as an honest broker to overcome turf battles.

A COS can improve, worsen, or even enable the worst instincts and impulses of the chief executive in governing foreign policy. The COS and the chief executive must have a working relationship that can govern and lead foreign policy. The COS is a necessary and vital resource to a chief executive with the solemn responsibility to serve the nation and its interests.

[1] Toosi, Nahal. 2017. “Can Tillerson Calm the Chaos at State?” Politico. January 31: https://www.politico.com/story/2017/01/can-rex-tillerson-bring-order-to-state-department-234448

[2] Joshua Zeitz, “The Last Time a General Propped Up a President.” Politico, July 29: https://www.politico.com/magazine/story/2017/07/29/the-last-time-a-general-propped-up-a-president-215438

[3] Quoted in Bradley Patterson, To Serve the President: Continuity and Innovation in the White House Staff Washington, D.C.: Brookings Institution, 2008: 40.

[4] Jo Becker and Scott Shane, “Secret ‘Kill List’ Proves a Test of Obama’s Principles and Will.” New York Times, May 29, 2012: https://www.nytimes.com/2012/05/29/world/obamas-leadership-in-war-on-al-qaeda.html

[5] Chris Whipple, “Why No One Wants to be Chief of Staff.” Washington Post. December 12, 2020: https://www.washingtonpost.com/opinions/why-no-one-wants-to-be-chief-of-staff/2018/12/12/c13acbf2-fe48-11e8-ad40-cdfd0e0dd65a_story.htmlhttps:/www.washingtonpost.com/opinions/why-no-one-wants-to-be-chief-of-staff/2018/12/12/c13acbf2-fe48-11e8-ad40-cdfd0e0dd65a_story.html