The US. first suggested a pact to Australia in the wake of the US-Japan Security Treaty and fears of Japanese rearmament. This was called ANZUS (Australia New Zealand United States) and was formed on the 1st of September 1951. The signatories agreed to maintain a consultative relationship for their collective security. In the 1980s New Zealand refused to let ships carrying nuclear weapons dock at its ports; the US, refusing to identify its nuclear-armed ships, suspended its treaty obligations to New Zealand in 1986, and the treaty has since been non-operative with reference to New Zealand. Over the years, australia has followed america into many battles including the Korean War, Vietnam War, Gulf War and both Iraq Wars; all without the invocation of ANZUS. The alliance has only been been invoked once, for the invasion of Afganistan.
The strenghth of the relationship has fluctuated over the years however, it has never been stronger than in 2001 after the september 11 attacks in America. John Howard, the Prime Minister of the time, was