He then moved to government during the Harry S. Truman administration, when Truman appointed him ambassador to Argentina in April 1951. Next he was ambassador to Italy in February 1952. From November 1953 until November 1956 he was president of the American Red Cross. In November 1956 he was appointed ambassador to India and Nepal by Dwight D. Eisenhower, and sworn in December 1956, where he played a crucial role in the covert alliance between the two powers against China. He was replaced by John Kenneth Galbraith in 1961. During 1962 he acted as U.S. mediator in the New York Agreement over Western New Guinea.