As such he was a strong believer in making efforts towards international cooperation. He was a member of the board of trustees of the World Peace Foundation in the early 1950s. During 1952–53 he was one of five members of the State Department Panel of Consultants on Disarmament and played a significant role in the panel's stark report about the dangers of nuclear weapons and relations with the Soviet Union.
From 1954, he was inaugural American secretary of the annual Bilderberg conference which discusses matters relating to European-American relations. In 1962–63, he presented a plan to solve the Palestinian refugee crisis. In 1969, he served as an alternate delegate on the US delegation to the United Nations, working under Ambassador Charles W. Yost.