John Sullivan Headshot

John Sullivan

Former Deputy Secretary of State and US Ambassador to the Russian Federation

John Sullivan Headshot


Ambassador John J. Sullivan, former US deputy secretary of state and former US ambassador to the Russian Federation, is a partner in Mayer Brown’s Washington, DC, and New York offices and colead of the firm’s national security practice. He is also a distinguished fellow at the Walsh School of Foreign Service of Georgetown University. As a leading authority on foreign affairs, Sullivan is quoted frequently in national media and is a contributor to CBS News.

Sullivan advises clients on global risk and foreign policy, US sanctions and export controls, international trade disputes and regulation, foreign investment, and other sensitive issues at the intersection of international commerce and national security policy. In addition to his expertise in foreign policy and, in particular, US-Russia relations, he has worked extensively on trade issues important to multinational companies doing business around the world, including as the US deputy secretary of commerce. 

Sullivan’s career spans four decades in the public sector and private law practice, and he has served five presidents in prominent diplomatic and legal positions. Most recently he was US ambassador to the Russian Federation from December 2019 to October 2022, a period spanning the presidencies of Donald Trump and Joe Biden. Before that, he was the deputy secretary of state and served as acting secretary of state for several weeks in 2018. 

Previously, he served by appointment of the Obama administration as chair of the US-Iraq Business Dialogue. He also held senior positions in the Departments of Justice, Defense, and Commerce in two prior administrations. 

In addition to cofounding the national security practice at Mayer Brown, Sullivan has also been a member of the firm’s Supreme Court and appellate practice. He received his bachelor’s degree from Brown University and his law degree from Columbia Law School, where he was book reviews editor of the Columbia Law Review

Sullivan is a member of the American Academy of Diplomacy and a Distinguished Senior Fellow in the National Security Law Program at Columbia Law School. He is the recipient of numerous honors and awards, including the Secretary of State's Distinguished Service Award; the Department of State's Distinguished Honor Award; the Director of the Central Intelligence Agency's Ambassador of the Year Award; the Defense Intelligence Director's Award; the Chairman of the Joint Chiefs of Staff's Joint Meritorious Civilian Service Award; the Secretary of Defense's Medal for Exceptional Public Service; and the Columbia Law School, DC Alumni Association, Distinguished Alumnus Award.