The main role of the Royal Australian Navy in the two decades following the end of Australia's involvement in the Vietnam War was supporting Australian diplomatic initiatives. In line with this goal the RAN exercised with the navies of Australia's allies and provided support to civil authorities in Australia and the South Pacific. The RAN's main military concern from the 1970s was the activities of the Soviet Navy in the Indian Ocean. These concerns lead to increased co-operation with the United States Navy and the development of the RAN's main base in Western Australia, .