He also served as Senior Advisor on Foreign Fighters in the Bureau of Counterterrorism in the Department of State from September 2015 to January 2017.

[2] Walles was sworn in as Ambassador to Tunisia by Secretary of State Hillary Clinton on June 21, 2012, and he presented his credentials to Tunisian President Marzouki on July 24, 2012.

He was the Ambassador in Tunis when the U.S. Embassy was attacked on September 14, 2012, in the wake of the Innocence of Muslims controversy.

[3] In that capacity, Walles was instructed to inform Palestinian President Mahmoud Abbas that the Hamas government was unacceptable.

[4] Walles also served as Deputy Chief of Mission at the U.S. Embassy in Athens from 2003 to 2005, as Deputy Principal Officer at the U.S. Consulate General in Jerusalem from 1996 to 1998, as Economic Officer at the U.S. Embassy in Tel Aviv from 1988 to 1991, and as Vice Consul in Amsterdam from 1982 to 1984.