His father was the United States Ambassador to Canada, Jay Pierrepont Moffat and his grandfather was the United States Ambassador to Japan, Joseph Clark Grew who tried hard to avert the pacific stage of the World War II.
He was a political officer in Bern, Switzerland, from 1969 to 1970, and Deputy Chief of Mission in Port of Spain, Trinidad and Tobago from 1971 to 1974.
He was Deputy Chief of Mission in Rabat, Morocco, from 1976 to 1980 and attended the Executive Seminar in National and International Affairs at the Foreign Service Institute from 1980 to 1981.
He was chargé d'affaires in N'Djamena, Chad, beginning in March 1982, taking over duties from John Blane, who had reopened the embassy that January.
He was a lineal descendant of Benjamin Franklin and John Jay, first US Chief Justice and negotiator of the Treaty of Paris, which formally ended the Revolutionary War and recognized the United States as a sovereign nation.