Key positions he held in the Foreign Service include Ambassador to the State of Qatar, 1995–1998;[3] Deputy Coordinator for Counterterrorism, responsible for the coordination of all U.S. Government counter-terrorism activities outside the United States,[4] 1993–1995; Political Advisor to the Commander in Chief, Central Command,[4] 1993 -1991; Deputy Chief of Mission and Political Officer in Amman, 1987–1991;[4] Director, Politico-Military Affairs, State Department, 1983–1986; Chargé d'affaires and Deputy Chief of Mission in Abu Dhabi,[4] 1980–1983; and Economic and Commercial Counselor in Damascus, Syria,[4] 1976–1980.
He also served in other diplomatic positions in Saudi Arabia, Lebanon, and Nicaragua, as well as in the Department of State.
He writes regular op-ed pieces for the Greek-American newspaper, The National Herald, in New York.
Ambassador Theros attended public schools in Michigan, Ohio, and the District of Columbia.
Ambassador Theros has also completed the Armed Forces Staff College at Norfolk, Virginia, and was appointed a Research Fellow at the National Defense University.