The ANZUS Treaty, originally signed in 1951, was a security agreement between Australia, New Zealand, and the United States. Its goal was to ensure mutual defense and strengthen cooperation in the Pacific region during the Cold War. Over the decades, the treaty’s relevance and functionality have been questioned due to evolving global politics and a significant rift between New Zealand and the United States. Despite these changes, the treaty has never been formally dissolved, prompting the ongoing question: does the ANZUS Treaty still exist in practice today?
Origins and Intent of the ANZUS Treaty
The ANZUS Treaty (Australia, New Zealand, United States Security Treaty) was signed on September 1, 1951, in response to the geopolitical instability following World War II and the rise of communism in the Asia-Pacific region. Its primary function was to formalize military cooperation among the three nations and serve as a deterrent against threats in the Pacific, especially from the Soviet Union and later China.
Under the treaty, the members agreed to consult one another in the event of an armed attack on any of them in the Pacific. While the treaty did not automatically require military action, it emphasized shared responsibility for regional security and collective defense.
Functioning During the Cold War
During the Cold War, the ANZUS Treaty was actively used as a framework for joint military exercises, intelligence sharing, and strategic cooperation. The three countries coordinated their defense policies and contributed troops to conflicts such as the Korean War and the Vietnam War.
Australia and New Zealand benefited from the security umbrella provided by the United States, while the U.S. gained reliable allies in the Pacific. ANZUS played an important role in reinforcing U.S. influence and promoting stability in the South Pacific and Southeast Asia.
The 1980s Rift with New Zealand
The treaty began to unravel in 1985 when New Zealand adopted a strong anti-nuclear stance under Prime Minister David Lange. New Zealand banned nuclear-armed or nuclear-powered ships from entering its ports, a policy that clashed directly with the U.S. Navy’s policy of neither confirming nor denying the presence of nuclear weapons aboard its vessels.
In response, the United States suspended its security obligations to New Zealand, stating that New Zealand could no longer be considered a full ally under the treaty. Military and intelligence ties were significantly reduced, though diplomatic relations continued. Australia chose to maintain its alliance with both nations and continued its bilateral military cooperation with the U.S.
Consequences of the Breakdown
- New Zealand was excluded from full ANZUS military cooperation.
- U.S.New Zealand military exercises and intelligence-sharing were halted or downgraded.
- Australia strengthened its independent bilateral defense agreements with the United States.
Although New Zealand remained a formal party to the ANZUS Treaty, the trilateral aspect of the alliance effectively ceased to function. From 1985 onward, ANZUS operated primarily as a bilateral arrangement between Australia and the United States.
AustraliaU.S. Alliance under ANZUS
Australia and the United States maintained and even deepened their defense ties through ANZUS. The alliance was reaffirmed after the September 11, 2001 attacks, when Australia invoked topic IV of the treaty, pledging support to the U.S. This marked the first and only time ANZUS was invoked in response to a direct attack on one of its members.
The U.S.Australia alliance remains active, with frequent joint military training, shared intelligence operations (especially under the Five Eyes agreement), and collaborative efforts in regional security initiatives. The ANZUS Treaty, in this bilateral form, continues to underpin Australia’s defense and foreign policy.
New Zealand’s Gradual Reintegration
While the full trilateral function of ANZUS has not been restored, U.S.New Zealand relations have gradually improved since the 1990s. New Zealand’s anti-nuclear stance remains, but diplomatic and security ties have strengthened in other areas.
By the early 2000s, military exercises between the U.S. and New Zealand resumed. In 2012, the Washington Declaration formalized defense cooperation between the two countries. This agreement, while not restoring New Zealand’s full ANZUS status, marked a new chapter of strategic partnership.
In 2016, a U.S. Navy vessel visited a New Zealand port for the first time in over 30 years, symbolizing thawing relations. However, the United States has not officially reinstated New Zealand’s full military alliance status under ANZUS.
Does the ANZUS Treaty Still Exist?
In legal and formal terms, yes the ANZUS Treaty still exists. None of the signatory nations have withdrawn from the treaty or declared it null and void. It remains a standing international agreement. However, the nature of its implementation has changed significantly since the 1980s.
Current Status of the Treaty
- The treaty remains in force and has not been terminated.
- It functions bilaterally between the United States and Australia as an active security alliance.
- New Zealand is still a party to the treaty but is not part of regular ANZUS military coordination.
- Separate defense arrangements, like the Washington Declaration, supplement trilateral cooperation without reviving ANZUS in its original form.
Therefore, while the ANZUS Treaty technically continues to exist, it does so in a modified, largely symbolic state for New Zealand and a more active state for Australia and the United States.
ANZUS in the 21st Century
In an era marked by new global threats such as cyber warfare, terrorism, and regional power shifts, particularly the rise of China, the ANZUS alliance has taken on renewed importance. Australia and the United States remain key partners in the Indo-Pacific strategy aimed at preserving a rules-based order and countering coercive behavior in the region.
New Zealand also plays a strategic role in Pacific security through peacekeeping, climate initiatives, and humanitarian efforts, even though its involvement under ANZUS remains limited. The growing defense and intelligence cooperation between all three countries indicates a convergence of strategic interests despite the treaty’s altered structure.
The ANZUS Treaty, signed in 1951, still legally exists, but its practical form has evolved over time. It continues to function as a bilateral alliance between Australia and the United States, with robust defense cooperation. While New Zealand remains a signatory, its full participation has not been restored due to longstanding nuclear policy differences. Nevertheless, the broader strategic ties among the three nations are stronger than they were during the height of the dispute, and ANZUS remains a foundational element of Pacific regional security. Though not operating as it once did, the treaty endures adapted, but not abandoned.