To lead on nuclear disarmament, Australia must renounce the US umbrella

Australia and nuclear weapons have a complicated history.

The country went from a testing ground for the UK’s nuclear program in the 1950s to a potential proliferator in the 1960s. In the 1980s, it helped establish a nuclear weapons-free zone, even as it came to depend on a uniquely mysterious US nuclear umbrella, which remained unconfirmed by Washington for decades.

Today, Canberra’s nuclear weapons policy is defined by a contradiction: It affirms the value of arms control and disarmament even as it leans ever more heavily on the US nuclear arsenal as a defensive backstop. This dissonance serves neither the cause of nuclear disarmament nor Australia’s security and holds the country back on both fronts.

The re-election of Donald Trump as US president has precipitated a broader dissonance in Australian policy. As other US allies are gradually trying to decrease their reliance on an increasingly erratic Washington, most Aussie politicians are unwilling to even discuss the issue. The government in Canberra is in fact pursuing deeper military ties than ever, with Washington having access to more than half of Australia’s military bases, to the point that many in the country are expressing concerns about the extent of the US influence. Few Australians want to end the alliance, but the proportion who believe the United States can be relied upon to aid the country if attacked has fallen by almost half in just three years.

Australia needs a serious public debate about the direction of its foreign policy and the future of its relationship with the United States. In the process, the country should choose a coherent direction for its nuclear policy. Most voters would prefer disarmament.

Testing ground. From 1952 to 1957, the United Kingdom conducted its first 12 nuclear explosive tests in Australia, all of them atmospheric. The Australian government was eager to cooperate, given its close relationship with the United Kingdom and out of hopes that London would share nuclear technology for power generation. Thousands of Aboriginal people were forced off their lands for the tests, and British personnel involved maintain that the government covered up the extent of the negative health effects.

By the end of the decade, fearing what it viewed as growing Communist expansionism in Asia, the Australian government began to seriously consider the idea of acquiring its own nuclear weapons. In 1961, Prime Minister Robert Menzies requested, and failed to receive, a promise from London to provide Canberra “if ever necessary, with a nuclear capability.”

This interest intensified significantly after China conducted its first nuclear test in 1964. But from the beginning, the idea suffered from a lack of realism: With no nuclear reactors, any weapons program would have to be built from scratch at enormous cost. Most senior politicians and civil servants opposed the idea, but it retained a small, vocal clique of supporters throughout the Cold War.

When the Nuclear Non-Proliferation Treaty (NPT) opened for signature in 1968, Australia did not initially join, as the government was determined to keep the nuclear option on the table. By 1970, however, fierce internal opposition as well as pressure from the United States forced Prime Minister John Gorton—a staunch nationalist and anti-Communist—to concede and sign the treaty. Gorton continued advocating for an Australian bomb until he was ousted the next year, and the country would not ratify the NPT until 1973.

As part of its diplomatic effort, Washington attempted to assuage Canberra’s security concerns. A May 1968 diplomatic cable promised that “military allies of the United States … are already covered by the nuclear protection of the United States” and that “Australia is an especially close ally,” pointing to the country’s participation in the Vietnam War. This cable is the earliest available evidence of any specific US nuclear pledge to Australia.

Proliferation into plowshares. Abandoning its brief nuclear ambitions, Australia became a prominent voice on arms control and disarmament.

In 1985, Australia and 12 other Pacific states signed the Treaty of Rarotonga, establishing the South Pacific Nuclear Free Zone that prohibits the stationing, manufacturing, or testing of nuclear weapons in a 200 million square kilometer (37 million square mile) zone—almost a fifth of the Earth’s surface. Almost all the land included in the treaty is Australian.

A decade later, Prime Minister Paul Keating organized the “Canberra Commission on the Elimination of Nuclear Weapons,” which produced a series of recommendations on achieving global nuclear disarmament. Australia also played a prominent role in negotiations for the Comprehensive Test Ban Treaty (CTBT) and formally brought the treaty’s text to the UN General Assembly. Since signing in 1996, Canberra has remained a vocal supporter of the treaty, even as it has yet to formally come into force.

Initially, this disarmament diplomacy had a partisan political flavor, as NPT ratification, the Treaty of Rarotonga, and the Canberra Commission all took place under governments of the center-left Labor Party. However, as the years passed, support for this anti-nuclear stance grew into a near consensus among the Australian public. When France resumed nuclear tests in the Pacific in 1995, it sparked universal outrage in Australia. And when the center-right Liberal Party took power the following year, it continued to work toward the finalization and signing of the CTBT.

In the 21st century, the split on nuclear weapons has re-asserted itself in Australian politics. The Liberal governments of Malcolm Turnbull and Scott Morrison opposed the 2017 Treaty on the Prohibition of Nuclear Weapons (TPNW, also known as the “ban treaty”) from the beginning, voting against the opening of negotiations at the UN and then boycotting them when they began. The government claimed the ban treaty “ignores the realities of the global security environment,” is ineffective, and is incompatible with the country’s alliance with the United States.

By contrast, the Labor Party and now-Prime Minister Anthony Albanese in particular have supported the ban treaty from the beginning. Every party manifesto since the treaty’s signing has included a pledge to join. When Labor under Albanese took power in 2022, Australia ceased its official opposition to the treaty at the UN, and the party’s 2023 manifesto reiterated that “Labor in government will sign and ratify the Ban Treaty.”

The invisible umbrella.  After 1968, the US nuclear guarantee quietly became a pillar of Australian defense policy. By the 1970s, the Australian government was discussing the umbrella internally as an established fact. But it was not until Australia’s 1993 Strategic Review, which fed into the 1994 Defense White Paper, that the policy was made public. Even then, it was entirely one-sided: Washington itself never acknowledged offering any nuclear guarantee to Canberra, even as it publicly reaffirmed its commitments to NATO, Japan, and South Korea at every opportunity (though it did not contract Australian statements either). As recently as the late 2010s, it was a matter of academic debate whether the nuclear umbrella really existed.

Politicians and officials in Canberra pointed to the ANZUS Treaty as the source of the nuclear guarantee. But New Zealand—also a party to ANZUS—has rejected the idea that the treaty includes a nuclear component and vehemently opposed the US nuclear policy in general. (This caused Washington to partially suspend its obligations to New Zealand in 1985). Based on documentary research and interviews with politicians, Australian scholar Richard Tanter concluded in 2011 that the umbrella was based entirely on “an understanding between officials” in the two countries, and that the US assurance was conditioned on Australia being under a nuclear attack.

This ambiguity was only conclusively resolved in October 2022, when the US Nuclear Posture Review finally listed Australia alongside Japan and South Korea as a recipient of “strong and credible nuclear deterrence in the Indo-Pacific.”

Pulled in two directions. The year 2022 seemed to set the stage for a reckoning with Australia finally receiving the long-coveted, unambiguous public confirmation of its US nuclear umbrella. But a few months earlier, the Labor Party—led by longtime ban treaty supporter Albanese—had just taken power. Four years later, however, Australian nuclear weapons policy remains in tension. The Albanese government has taken no steps toward joining the ban treaty, despite the 2023 election promise to sign and ratify the treaty. When asked recently, Labor Party figures have dodged the question, saying that the government “is pursuing the NPT” and “shares the [ban treaty]’s ambition.”

The Labor government has also thrown its full support behind the 2021 AUKUS agreement, under which the United Kingdom and the United States are supporting Australia in developing nuclear-powered—but conventionally-armed—submarines. While the deal does not involve nuclear weapons as such, it will see Australia provided with weapons-grade (93-percent enriched) uranium to fuel the submarines, sparking opposition in the South Pacific and globally.

Ultimately, the incoherence of Australian policy is self-defeating.

Canberra is not fully credible either as a recipient of US nuclear guarantees or as a disarmament advocate. It is the only country in the world which relies on a nuclear umbrella while being part of a nuclear weapon-free zone. The Treaty of Rarotonga does not prohibit extended deterrence explicitly, but such arrangements clearly violate the agreement in spirit, particularly the pledge not to “encourage” any other state to manufacture nuclear weapons.

The treaty does explicitly prohibit hosting nuclear weapons on Australian soil. Canberra finds itself increasingly straining this obligation as it tries to deepen its defense ties with the United States, including more frequent visits by US warships to Australian ports and the rotation of nuclear-capable bombers through Australian bases. It relies on the United States’s longstanding policy of “neither confirming nor denying” the presence of nuclear weapons on ships and aircraft, while also insisting on a difference between “stationing” nuclear weapons and them merely “transiting” or “visiting.”

Policymakers are also limited by public opinion. While the disarmament consensus in Australia has weakened, polls consistently find that a large majority of Australians want to accede to the ban treaty. In that context, no government wants to be seen clearly violating or disavowing the country’s existing treaty obligations.

Squaring the circle. Canberra needs to resolve this tension; otherwise, it will continue to suffer the worst of both worlds. The simplest solution would be for the Labor government to fulfill its mandate to renounce the US nuclear umbrella and join the ban treaty.

The umbrella is not necessary for Australia’s security. The country’s remote, insular geography makes invasion highly implausible. Proponents of the umbrella argue that it is still needed to deter potential nuclear attack or coercion from Beijing, but that same geography makes a Chinese nuclear threat to Australia alone—bypassing South Korea, Japan, Guam, and other targets already likely to draw a US response—equally improbable. Moreover, non-nuclear states are not automatically vulnerable to coercion: In fact, successful nuclear blackmail is very rare.

Opponents of Australian accession to the ban treaty claim that it would risk collapsing the alliance with the United States. This argument is weak. The alliance and the nuclear umbrella are not synonymous; Washington has many allies to whom it does not offer a nuclear umbrella, and Australia would simply be seeking to become one. Thailand and the Philippines—two regional US allies—have joined the ban treaty. So has New Zealand—whose alliance is based in the same treaty as Australia’s—and Wellington’s relationship with Washington is stronger than it has been in decades. Albanese said himself that on the ban treaty, “we can disagree with our friends in the short term, while maintaining those relations.”

Australia joining the ban treaty would certainly change the nature of the alliance. But at a time when almost all other US allies globally are realizing that the United States may no longer be the reliable ally they once thought—and may even be hostile—Canberra should be reconsidering going all-in on partnership with Washington. Joining the ban treaty would be both a step toward a more autonomous foreign policy and a chance for Australia to be a leader on nuclear disarmament once more.