Harry Truman actually said...
May I add a personal word of thanks to you, Mr. Secretary General, for the strong and steadfast manner in which you have performed the high duty entrusted to you as the impartial servant of the United Nations and its 55 Member Countries in the cause of peace.
Context
Message to Secretary General Trygve Lie on the Anniversary of the United Nations First Meeting in the United States.
03/24/1947