Following signing of the Instrument of Surrender, September 2, 1945, Ryukyu Islands were administered by Department of the Navy, September 21, 1945-June 30, 1946, with Commanding Officer, Naval Operating Base, Okinawa functioning as chief military government officer under authority of Commander-in-Chief U.S. Pacific Fleet. Transfer of administration from Department of the Navy to War Department authorized by Joint Chiefs of Staff (JCS) approval, April 1, 1946, of JCS 819/11, March 5, 1946, with added proviso of JCS 819/12, March 22, 1946. Pursuant to implementing instructions of General Headquarters U.S. Army Forces in the Pacific (GHQ AFPAC), Okinawa Base Command redesignated Ryukyus Command, effective July 1, 1946, by General Order 162, Headquarters U.S. Army Forces, Western Pacific, and made responsible for administration under a Deputy Commander for Military Government. Ryukyu Islands administered successively by Ryukyus Command, July 1-November 30, 1946; Philippines-Ryukyus Command, December 1, 1946-July 31, 1948; and Ryukyuan Command, August 1, 1948-December 15, 1950. USCAR established, effective December 15, 1950, by a directive of Headquarters Far East Command (HQ FEC, formerly GHQ AFPAC), AG 091.1 (5 Dec 50) RCA, December 5, 1950, implementing a JCS memorandum, SM 2474-50, October 11, 1950, directing Commander-in-Chief Far East, Gen. Douglas MacArthur, to organize a civil administration for the Ryukyu Islands in accordance with JCS 1231/14, October 4, 1950. USCAR continued to function under Department of the Army (formerly War Department), 1950-71. Amami Island Group of Ryukyu Islands was returned to Japan by the Agreement between the United States of America and Japan concerning the Amami Islands, signed December 24, 1953, and made effective December 25, 1953. USCAR abolished following entrance into force, May 15, 1972, of the Agreement between the United States of America and Japan concerning the Ryukyu Islands and the Daito Islands, signed June 17, 1971, by which the remaining island groups of the Ryukyu Islands, including the Okinawa Island Group, were returned to Japan.