World War II was a major turning point for both countries, as they realised that they could no longer rely on the protection of Britain. Australia was particularly struck by this realisation, as it was directly targeted by the Empire of Japan, with Darwin bombed and Broome attacked. Subsequently, both countries sought closer ties with the United States. This resulted in the ANZUS pact of 1951, in which Australia, New Zealand and the United States agreed to defend each other in the event of enemy attack. Although no such attack occurred until, arguably, 11 September 2001, Australia and New Zealand both contributed troops to the Korean and Vietnam Wars. Australia's contribution to the Vietnam War in particular was much larger than New Zealand's; while Australia introduced conscription, New Zealand sent only a token force. Australia has continued to be more committed to the American alliance, ANZUS, than New Zealand; although both countries felt considerable unease about American military policy in the 1980s, New Zealand angered the United States by refusing port access to nuclear ships into its nuclear-free zone from 1985 and in retaliation, the United States 'suspended' its obligations otherwise owed under the alliance treaty to New Zealand. Australia has made a significant contribution to the Iraq War, while New Zealand's much smaller military contribution was limited to UN-authorised reconstruction tasks.