Ambassador Butler assumed the position of Principal Deputy High Representative on March 28, 2005, coming directly from his previous position in Skopje where he was the American Ambassador to the Republic of Macedonia. 

Ambassador Butler, currently detached from the U.S. State Department, has been a member of the U.S. Senior Foreign Service since 1997, joining the Foreign Service in 1976. From 1997-1999 he was at the White House on the National Security Council staff as Director for European Affairs where he was directly responsible for Presidential involvement in achieving the Belfast "Good Friday" agreement in the Northern Ireland peace process. He also covered the European Union, preparing the then twice-yearly U.S.-EU Summits, as well as handling relations with the Nordic states, UK, Ireland and Germany. Ambassador Butler was Deputy Chief of the U.S. Embassies in Copenhagen, Denmark, in Dublin, Ireland and Belgrade, Serbia-Montenegro. In Belgrade he worked on the Bosnian peace process that culminated in the Dayton Accord in December, 1995. While in Belgrade, he became acting Chief of Mission for most of 1996, assisting in implementing the Dayton Accord and opening the first U.S. Office in Kosovo. In 1993, he was on special assignment with the OSCE mission to the former Yugoslavia, where he opened the Pec, Kosovo branch office to report and mediate human rights issues. Other overseas postings include two tours in Helsinki, Finland dealing with economic and trade policy, a tour in Bulgaria, as Economic/Commercial Officer and later head of the Political/Economic Section, and Brasilia, Brazil as an economic policy officer. State Department Washington assignments include Deputy Director of the office responsible for EU and OECD Affairs, Special Assistant to the Undersecretary for Political Affairs and Senior Watch Officer in the Secretary's Operations Center.

Ambassador Butler earned his B.A. at Bowdoin College and did graduate work at the University of Michigan (MBA program) and at Princeton's Woodrow Wilson School (International Economics). His wife, Linda d'Obry Willemoes Butler, accompanies Ambassador Butler.