On May 10, 1979, four of the Trust Territory districts ratified a new constitution to become the Federated States of Micronesia. The neighboring trust districts of Palau, the Marshall Islands, and the Northern Mariana Islands chose not to participate. The FSM became independent and signed a Compact of Free Association with the U.S. in 1986. An Amended and Perpetual Compact entered into force in June 2004.