Robert Kagan writes a monthly foreign affairs column for The Post. He is also a senior fellow at the Brookings Institution. Kagan served in the State Department from 1984 to 1988 as a member of the Policy Planning Staff, as principal speechwriter for Secretary of State George P. Shultz, and as deputy for policy in the Bureau of Inter-American Affairs. He is the author of “The Return of History and the End of Dreams” (2008), “Dangerous Nation: America’s Place in the World from its Earliest Days to the Dawn of the Twentieth Century” (2006), “Of Paradise and Power” (2003), and “A Twilight Struggle: American Power and Nicaragua, 1977-1990” (1996), and he is co-editor with William Kristol of “Present Dangers: Crisis and Opportunity in American Foreign Policy” (2000).