The Sudanese Armed Forces (SAF) are the armed forces of the Republic of Sudan. They number, according to 2011 IISS estimates, 109,300. They comprises Land Forces, a Navy, an Air Force, and the Popular Defence Forces. They also previously had Joint Integrated Units formed together with its rebel enemies the Sudan People's Liberation Army. The Armed Forces operate under the authority of the People's Armed Forces Act 1986. In 1991, the Library of Congress used the term 'Sudan People's Armed Forces' to refer to the entire armed forces, but by the late 2000s (decade), the 'Sudanese Armed Forces' term was most widespread. In 2004, the Federal Research Division of the Library of Congress estimated that the Popular Defence Forces, the military wing of the National Islamic Front, consists of 10,000 active members, with 85,000 reserves. It has been deployed alongside regular army units against various rebel groups.