He formerly served as the Executive Director for Research of the Belfer Center for Science and International Affairs at the John F. Kennedy School of Government at Harvard University.

[2][3] In the position, Samore "served as the principal advisor to the President on all matters relating to arms control and the prevention of weapons of mass destruction proliferation and WMD terrorism, and coordinated United States government activities, initiatives, and programs to prevent proliferation and WMD terrorism and promote international arms control efforts.

"[1] He is credited with working with Laura Holgate, the NSC Senior Director for WMD Terrorism and Threat Reduction, to first implement Gift basket diplomacy.

[4] From 1996 to 2000, Samore served as Special Assistant to President Bill Clinton and Senior Director for Nonproliferation and Export Controls at the National Security Council.

[5] Samore is an Advisory Board member of the advocacy group United Against Nuclear Iran.