How has counter-terrorism changed from 9/11 to today over three presidencies? To answer that question, Ryan Evans sat down with two guests with deep perspective on counter-terrorism: Colin Kahl was the national security adviser to Vice President Biden and, earlier in the Obama administration, was the deputy assistant secretary of defense for the Middle East. He is now associate professor in the Security Studies Program at the Georgetown School of Foreign Service. Stephen Tankel is an assistant professor in the School of International Service at American University, an adjunct senior fellow at CNAS, and a senior editor at War on the Rocks. He previously served as a senior adviser for Asian and Pacific security affairs at the Department of Defense. Stephen is the author of the forthcoming book, With Us and Against Us: America's Partners in the War on Terror.