 During World War II, a significant portion of the Japanese fleet was based in Truk Lagoon.In February 1944, Operation Hailstone, one of the most important naval battles of the war, took place at Truk, in which many Japanese support vessels and aircraft were destroyed.Following World War II, it was administered by the United States under United Nations auspices in 1947 as part of the Trust Territory of the Pacific Islands pursuant to Security Council Resolution 21.