In 1941, Buss left USC and flew to Manila to serve as the executive assistant to the US High Commissioner in the Philippines, a position he held for a year. When the Japanese army began invading the Philippines in December 1941, he opted not to flee Manila, making him the highest-ranking official to remain in the city.
Buss was captured by the Japanese in January of 1942 and was interned for six months with all the members of the High Commissioner's office who had stayed in Manila. In June of 1942, he was taken from the Philippines and sent to Tokyo, where he remained in captivity until his repatriation in September 1943.
[Claude Buss, believed to have been taken by Carl Mydans while aboard the MS Gripsholm in late 1943]
After his return to the United States, Buss resigned from his position in the High Commissioner's office and was put in charge of the San Francisco department of the Office of War Information, where he remained until the end of the war. After the Japanese surrender, he served as a consultant to both the Strategic Bombing Survey and MacArthur's staff for the Allied occupation of Japan.