Ambassador Timo S. Koster is a former career diplomat at the Dutch Ministry of Foreign Affairs and nonresident senior fellow with the Atlantic Council’s Scowcroft Center for Strategy and Security.

From 2018 to 2020, Ambassador Koster served as ambassador-at-large with a focus on security policy and cyber. From 2012 to 2018, he was director for defense policy and capabilities at NATO headquarters in Brussels. After finishing his law degree at the University of Amsterdam, Ambassador Koster joined the diplomatic academy of the Ministry of Foreign Affairs of the Netherlands in 1991. His first appointment was at the Royal Netherlands Embassy in Nairobi, Kenya. He returned to The Hague in 1994, where he served in several positions within the Ministry, including a stint as private secretary to the Minister for European Affairs. From 1998 to 2001 he served at the Netherlands Embassy in London as head of the Economic Department. In 2001, Ambassador Koster became acting director for European integration at the Ministry of Economic Affairs, after which he served as a project director at the Ministry for Foreign Affairs. In 2003, Koster was appointed deputy ambassador at the Royal Netherlands Embassy in Athens, Greece. In 2008 he moved to Brussels where he served as defense adviser at the Netherlands Permanent Representation to NATO until 2012, when he moved to the position of director for defense policy and capabilities in the NATO International Staff. Ambassador Koster is married with two sons and two daughters.