After almost four decades under US administration as the easternmost part of the UN Trust Territory of the Pacific Islands, the Marshall Islands attained independence in 1986 under a Compact of Free Association. Compensation claims continue as a result of US nuclear testing conducted on some of the atolls between 1947 and 1962 (67 tests total). The Marshall Islands hosts the US Army Kwajalein Atoll Reagan Missile Test Site, a key installation in the US missile defense network. Kwajalein also hosts one of four dedicated ground antennas that assist in the operation of the Global Positioning System (GPS) navigation system (the others are at Cape Canaveral, Florida (US), on Ascension (Saint Helena, Ascension, and Tristan da Cunha), and at Diego Garcia (British Indian Ocean Territory)).