The Pacific Proving Grounds was the name used to describe a number of sites in the Marshall Islands and a few other sites in the Pacific Ocean, used by the United States to conduct nuclear testing at various times between 1946 and 1962. In July 1947, after the first atomic weapons testing at Bikini Atoll, the United States entered into an agreement with the United Nations to govern the Trust Territory of the Pacific Islands as a strategic trusteeship territory. The Trust Territory is composed of 2,000 islands spread over of the North Pacific Ocean. On July 23, 1947, the United States Atomic Energy Commission announced the establishment of the Pacific Proving Grounds.