Ambassador Ušackas was the European Union's Ambassador to Russia (2013-2017), the former Foreign Minister of Lithuania, as well as the former Ambassador to the USA, UK and the European Union Special Representative and Head of the European Union Delegation in Afghanistan.

In 1991, he joined the Lithuanian Ministry of Foreign Affairs. In his distinguished career in the Foreign Service, he served as Counselor to the Lithuanian Mission to both the EU and NATO from 1992 to 1996; Political Director of the Lithuanian Ministry of Foreign Affairs from 1996 to 1999; Deputy Minister of Foreign Affairs of Lithuania and Chief Negotiator for Lithuania’s Accession to the European Union from 1999 to 2001; Lithuanian Ambassador to the United States of America and United Mexican States from 2001 to 2006; Ambassador of Lithuania to the Court of St. James from 2006 – 2008; and was Lithuanian Foreign Minister from 2008 to 2010.