New Zealand is a signatory of the ANZUS treaty, a defence pact between New Zealand, Australia and the United States dating from 1951. After the 1986 anti-nuclear legislation that refused access of nuclear-powered or armed vessels to ports, the USA withdrew its obligations to New Zealand under ANZUS, and ANZUS exercises are now bilateral between Australia and the United States. Under anti-nuclear legislation, any ship must declare whether it is nuclear-propelled or carrying nuclear weapons before entering New Zealand waters. Due to the US policy at that time of "neither confirm nor deny", ship visits ceased although NZ and the USA remained "good friends". Despite the Presidential Directive of 27 September 1991 that removed tactical nuclear weapons from U.S. surface ships, attack submarines, and naval aircraft, ship visits have not resumed. Despite signs of rapprochement in recent years, military relationships with the US remain limited.