Robert Kagan (born September 26, 1958) is an American historian, political scientist, and prominent neoconservative foreign policy commentator and expert renowned for his advocacy for robust U.S. global leadership, American primacy, and liberal internationalism. He is a leading critic of isolationist tendencies in U.S. foreign policy and has been influential in shaping neoconservative thought. Kagan earned a B.A. in history from Yale University in 1980, where he served as editor-in-chief of the Yale Political Monthly in 1979, crediting himself with reviving the publication. He later obtained a Master of Public Policy from Harvard University's John F. Kennedy School of Government in 1982 and a Ph.D. in history from American University in 1991. His early career included service in the U.S. State Department from 1984 to 1988, working on the Policy Planning Staff and as principal speechwriter for Secretary of State George P. Shultz.

Kagan co-founded the Project for the New American Century (PNAC) in 1997, a think tank that promoted neoconservative interventionist policies and significantly influenced U.S. foreign policy, including during the George W. Bush administration and the Iraq War. He has been a senior fellow at the Brookings Institution since 2010, focusing on international order and strategy through the Project on International Order and Strategy, where he holds the Stephen & Barbara Friedman Senior Fellow position. As a contributing columnist for The Washington Post since 1997, where he also served as editor at large, Kagan critiques U.S. foreign policy while advocating for liberal internationalism. His influential works include 'Dangerous Nation' (2006), 'The World America Made' (2012), and 'Rebellion: How Antiliberalism is Tearing America Apart — Again' (2024), which explore themes of U.S. exceptionalism, domestic political challenges, and threats to liberal democracy.

A leading voice in neoconservative circles, Kagan has been both praised and criticized for his hawkish stances on issues like the Iraq War. He has been a vocal critic of Donald Trump, describing his presidency as a threat to democratic norms, and endorsed Joe Biden in 2020. Kagan's work often critiques adversaries like Vladimir Putin and isolationist figures such as Pat Buchanan and Ron Paul. Born to a prominent academic family—his father, Donald Kagan, is a renowned Yale classicist—Kagan is married to diplomat Victoria Nuland, a career diplomat and former Under Secretary of State. His brother, Frederick Kagan, is also a foreign policy expert at the American Enterprise Institute. Kagan's Jewish heritage and neoconservative ideology have shaped his views on international order, emphasizing moral clarity in U.S. foreign engagements. Despite his influence, Kagan has faced criticism for his role in promoting policies seen as overly interventionist, particularly in the Middle East.