The treaty was one of a series that the United States formed in the 1949–1955 era as part of its collective response to the threat of communism during the Cold War.

In late 2012, the United States lifted a 26-year-old ban on visits by New Zealand warships to US Department of Defense and US Coast Guard bases around the world.

New Zealand maintains a nuclear-free zone as part of its foreign policy and is partially suspended from ANZUS, as the United States maintains an ambiguous policy whether or not the warships carry nuclear weapons and operates numerous nuclear-powered aircraft carriers and submarines; however New Zealand resumed key areas of the ANZUS treaty in 2007.

The two countries also operate several joint-defence facilities in Australia, mainly ground stations for spy satellite, and signals intelligence espionage in Southeast and East Asia as part of the ECHELON network.

However, the treaty did not include an automatic commitment to armed assistance like in NATO, with Spender expecting that this could not be ratified by the US Senate who would wish to retain the congressional power to declare war.

Australian Prime Minister Malcolm Fraser of the Liberal Party had agreed to provide monitoring sites near Sydney for this purpose.

[20] However, in 1985, the newly elected Prime Minister Bob Hawke, of the Labor Party, withdrew Australia from the testing programme, sparking criticism from the Reagan Administration.

The Labor left-wing faction also strongly sympathized with the New Zealand Fourth Labour Government's anti-nuclear policy and supported a South Pacific Nuclear Free Zone.

[21][22][23] To preserve its joint Australian-US military communications facilities, the Reagan Administration also had to assure the Hawke Government that those installations would not be used in the Strategic Defense Initiative project, which the Australian Labor Party strongly opposed.

[23] Unlike New Zealand, Australia continued to allow US warships to visit its ports and to participate in joint military exercises with the United States.

Due to a current of anti-nuclear sentiment within New Zealand, tension had long been present between ANZUS members as the United States is a declared nuclear power.

An opinion poll in New Zealand in 1991,[32] showed 54% of those sampled preferred to let the treaty lapse rather than accept visits again by nuclear-armed or nuclear-powered vessels.

[34] On 10 July 1985, agents of the French Directorate-General for External Security bombed the Greenpeace protest vessel Rainbow Warrior in Auckland, causing one death.

The lack of condemnation by Western leaders to this violation of a friendly state's sovereignty caused a great deal of change in New Zealand's foreign and defence policy,[35] and strengthened domestic opposition to the military application of nuclear technology in any form.

[37] Between 1999 and 2003, the armed forces of Australia and New Zealand deployed together in a large scale operation in East Timor, to prevent pro-Indonesian militia from overturning a vote for independence on the region.

One topic that became prominent in the 2000s was the implications in the case of a hypothetical attack by the People's Republic of China against Taiwan, who would likely receive American support.

While Australia has strong cultural and economic ties with the United States, it also has an increasingly important trade relationship with mainland China.

At the second meeting, in San Francisco in 1986, the United States announced that it was suspending its treaty security obligations to New Zealand pending the restoration of port access.

[42] One commentator in Australia has argued that the treaty should be re-negotiated in the context of terrorism, the modern role of the United Nations and as a purely US–Australian alliance.

"Rather than trying to change each other's minds on the nuclear issue, which is a bit of a relic, I think we should focus on things we can make work" he told an Australian newspaper.

[47] On 4 February 2008, US Trade Representative Susan Schwab announced that the United States will join negotiations with four Asia–Pacific countries: Brunei, Chile, New Zealand and Singapore to be known as the "P-4".

These countries already have a FTA called the Trans-Pacific Strategic Economic Partnership and the United States will be looking to become involved in the "vitally important emerging Asia-Pacific region".

The signing of the declaration ended the ANZUS dispute of the past 25 years, and it was later revealed the US and New Zealand had resumed military co-operation in eight areas in 2007.

New Zealand and the United States signed the Washington Declaration on 19 June 2012 "to promote and strengthen closer bilateral defense and security cooperation".