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Mark A. Sullo is a Supervisory Special Agent (SSA) and a member of the Senior Foreign Service. Currently, he is Deputy Assistant Secretary of the Bureau of Diplomatic Security and Assistant Director of the Diplomatic Security Service (DSS) for Domestic Operations. In this capacity he is responsible for all DSS protective operations, counterintelligence, criminal investigations, domestic facility protection, and operations at all DSS Field and Resident Offices throughout the United States. He serves concurrently as the interagency chair of the International Security Event Group – coordinating all U.S. security and law enforcement planning for major overseas events such as the Olympic Games.

Mr. Sullo most recently served as Diplomatic Security’s Chief of Staff where he assisted in overseeing all law enforcement and security issues impacting the Department on behalf of the Assistant Secretary of State for Diplomatic Security. He entered the Foreign Service in 2002. His overseas assignments include service as the Senior Deputy Regional Security Officer (RSO) for the U.S. Mission to Iraq; RSO at the U.S. Embassy in Bahrain; RSO for three Provincial Reconstruction Teams in southern Iraq; and Assistant RSO at the U.S. Embassy in Kuwait.

His DSS domestic assignments include the Office of Mobile Security Deployments; the Washington Field Office; Agent-in-Charge of the U.S. Ambassador to the United Nations protective detail; Branch Chief in the Office of Antiterrorism Assistance; High Threat Strategy Coordinator for all of the Department of State’s security training reforms following the 2012 Benghazi attacks; and Deputy Assistant Director of DSS for Protective Intelligence Investigations where he was responsible for overseeing terrorism and threat investigations directed against the Department, as well as DSS liaison relationships with the U.S. intelligence and counterterrorism communities. In addition, from 2014-2015, Mr. Sullo was Director for Counterterrorism at the National Security Council where he was responsible for coordinating mitigation measures among U.S. federal agencies to detect, disrupt, and respond to threats against all official and private American interests overseas on behalf of the Assistant to the President for Homeland Security and Counterterrorism, the National Security Advisor, and the President of the United States.

A former Marine Corps infantry officer, Mr. Sullo also served with the Defense Intelligence Agency and retired as a Reserve lieutenant colonel in 2015. Mr. Sullo holds a Bachelor of Arts in Mathematics from Western Kentucky University, a Master of Arts in Security Management from the George Washington University, and is a distinguished graduate of the National War College where he received a Master of Science in National Security Strategy.

U.S. Department of State

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