He formerly served as Dean of the Elliott School of International Affairs of the George Washington University, where he currently serves as Professor of International Affairs, Political Science, and Gender Studies.

[4] He was Senior Fellow in U.S. Security Policy at the International Institute for Strategic Studies in London (1988 to 1994).

In 1998 he joined the faculty of the Edmund A. Walsh School of Foreign Service at Georgetown University, becoming Director of Georgetown's Center for Peace and Security Studies in 2000.

He held that position until 2015, after which he continued at the school, as a faculty member with a research focus on international security.

[2] He is well-known at the George Washington University for wearing his signature orange necktie while giving lectures, except the week of Halloween.