The AUKUS security pact was announced in September 2021 by the US, Australia and UK amid relatively low expectations and mixed reactions globally, despite UK National Security Adviser Stephen Lovegrove calling it “perhaps the most significant capability collaboration anywhere in the world in the past six decades.” However, it is now gaining momentum. The latest wave of interest in AUKUS has come amid much speculation about Japan’s potential role in the so-called phase two of the alliance. However, the world’s fourth-largest economy is just one of several nations that have been mooted as potential partners in the last couple of years. Others include New Zealand, Canada, South Korea and Singapore. UK Defense Secretary Grant Shapps confirmed on Monday that consultations on future cooperation between AUKUS security pact partners and other nations will begin this year. Asian allies such as Japan, South Korea and Singapore would all bring key assets to the table, but full membership of AUKUS is not yet being proposed. Asian allies such as Japan, South Korea and Singapore would all bring key assets to the table Andrew Hammond Japan is planning to double its military budget, which will soon be the world’s third-largest. Meanwhile, South Korea has a capable military that has spent decades training and preparing for potential conflict with North Korea and Singapore has well-trained, high-tech naval and air forces. Beyond Asia, further-flung nations including Canada and New Zealand — both members of the Five Eyes intelligence alliance with the US, Australia and the UK — are also potential partners. Canada, for example, was backed for AUKUS membership by former UK Prime Ministers Boris Johnson and Liz Truss “to strengthen the West’s collective defenses.” Johnson has even said that Canada is the “most obvious next candidate,” in part because it had “fought, often heroically, for freedom” in the past. Canadian Prime Minister Justin Trudeau said this week that he had already held “excellent conversations” with London, Washington and Canberra over joining the AUKUS alliance. One key benefit for Canada of joining AUKUS is its need for new submarines (potentially nuclear-powered ones) to protect its coastline. Canada has the longest Arctic coastline in the world and it is under significant geopolitical scrutiny from an increasing number of nations. The potential Canadian need for nuclear-powered submarines relates back to the stage one founding of AUKUS in 2021, which was as a defense alliance focused on helping Australia acquire its first such vessels. Building from this, the next phase of AUKUS is centered on advanced capabilities and the sharing of technologies in areas such as hypersonic speed, quantum computing and undersea capabilities. However, a key challenge to the collaboration of Asian nations outside of AUKUS is the US’ restrictions on sharing technological secrets. To combat this, Japan has said it will try to introduce economic security legislation to allow it to classify more information as confidential and ask employees at companies with access to it to undergo security clearance checks, along with enhanced cybersecurity. The growing warmth between London and Canberra is bringing new relevance to this long-standing partnership Andrew Hammond The latest wave of phase two speculation concerning AUKUS underlines that, while some dismiss the importance of this deepening defense relationship, it is seen as hugely important in Washington, London and Canberra. Although the three nations are separated geographically, they have deep historical ties that are being rejuvenated in the 2020s. Take the example of the growing warmth between London and Canberra, which is bringing new relevance to this long-standing partnership. This includes plans for Australia to regularly host two of the Royal Navy’s offshore patrol vessels — a move that is expected to lay the groundwork for future rotations of larger UK ships and submarines and the possibility that UK military assets could be based permanently in Australia in the future. So, while AUKUS is a relatively new alliance, it is only the latest chapter in the long history of these nations’ security and political cooperation. The Five Eyes security alliance, for example, stemmed from the intelligence relationship that the US and UK enjoyed in the Second World War. This was institutionalized in the 1946 UKUSA Agreement. Canada, Australia and New Zealand, as former UK dominions, began representing themselves in the intelligence pact in the late 1940s and 1950s, which led to developments like the 1951 ANZUS treaty. To be sure, there have been some bumps in the road in recent years, including divergences over the use of Chinese 5G telecommunications technology. Australia and the US have been most vociferous in their opposition to such Chinese technology, with both banning the China-headquartered telecoms firms from supplying equipment to their 5G networks. However, the UK (alongside other Five Eyes allies New Zealand and Canada) previously had more nuanced positions. The governments of Theresa May and Johnson had considered allowing Chinese firms a limited role in building “non-core” parts of the nation’s 5G network. However, Johnson ultimately U-turned on this issue under pressure from Canberra and Washington. Had there been a big breach between the UK and Australia on this issue, intelligence sharing could have been curtailed, denting ties. One sign of the fact that AUKUS is such a big political call for the UK is the criticism from May, who has, in her capacity as a former premier, questioned whether the pact means London could be enveloped in a war with China over Taiwan, given the long-standing US security guarantees given to Taipei. This issue was fueled by comments made this week by US Deputy Secretary of State Kurt Campbell, who suggested that American submarines supplied to Australia could be deployed against China in any conflict over Taiwan. Taken together, the AUKUS project is therefore assuming new momentum. While any expansion of the alliance may be unlikely in the immediate term, collaboration with a range of partners in the Asia-Pacific and Americas appears increasingly possible. Andrew Hammond is an Associate at LSE IDEAS at the London School of Economics.