The 531st Bombardment Squadron was a unit of the US Air Force, first activated during World War II. After training as a heavy bomber unit in the United States, it moved to the Southwest Pacific Theater, entering combat in May 1943, flying combat missions from Australia while attached to the Royal Australian Air Force, earning two Distinguished Unit Citations and a Philippine Presidential Unit Citation. In 1945 it moved forward to the Philippines, then to Okinawa. Following V-J Day, the squadron returned to the Philippines and was inactivated there in February 1946.