The Australian Defence Force (ADF) is the military organization responsible for the defence of Australia. It consists of the Royal Australian Navy, the Australian Army, the Royal Australian Air Force and a number of 'tri-service' units. During the first decades of the 20th century, the Australian Government established three separate armed services. Each service had an independent chain of command. In 1976, the government made a strategic change and established the ADF to place the services under a single headquarters. Over time, the degree of integration has increased and tri-service headquarters, logistics and training institutions have supplanted many single-service establishments.