Mull (born April 30, 1958) is a Senior Foreign Service officer who was most recently the Acting Undersecretary of State for Political Affairs.
He previously served as United States Ambassador to Poland, Acting Assistant Secretary of State for Political-Military Affairs and United States Ambassador to Lithuania.Ambassador Mull holds the rank of Career Ambassador, the highest diplomatic rank in the United States Foreign Service.On September 18, 2015, Mull was appointed as the United States Lead Coordinator for Iran Nuclear Implementation, tasked with carrying out the terms of the Joint Comprehensive Plan of Action by United States Secretary of State John Kerry.