The AUKUS Trilateral Security Partnership, established in September 2021 between Australia, the United Kingdom, and the United States (US), rests on two main pillars. The first pillar provides for the US and the United Kingdom to supply Australia with nuclear-powered submarines by 2040. The second pillar, meanwhile, aims to enhance joint capabilities and interoperability among member states in strategic military-defense sectors. These sectors encompass advanced capabilities such as cyber, artificial intelligence, quantum technologies, undersea capabilities, hypersonic and counter-hypersonic capabilities, electronic warfare (EW), and innovation.
AUKUS’s second pillar is regarded as a major opportunity to strengthen industrial integration across the alliance, accelerate innovation, and secure long-term economic and technological growth. Always open to the participation of new members, AUKUS’s second pillar could also become one of the cornerstones of the security-defense alliance that Western actors are building in the Asia-Pacific. The question of expanding this pillar first arose back in 2021, while AUKUS was still being formed, and over time Canada, Japan, New Zealand, and South Korea have emerged as the main countries interested in joining AUKUS. However, this expansion is expected to take place not within AUKUS’s first pillar, but on a project basis within the second pillar. Accordingly, countries such as Canada, Japan, New Zealand, and South Korea would only be able to take part in projects announced in specific fields and technologies.
During the Shangri-La Dialogue security summit held in Singapore on 30 May 2026, the Defense Ministers of the US, the United Kingdom, and Australia announced the first major project under the second pillar.[i] his project envisages supporting a range of missions, including the protection of critical seabed infrastructure, surveillance and reconnaissance operations, strike missions, logistics support, undersea and surface warfare, mine countermeasures, electronic warfare, and contested littoral operations. Under this initiative, the first-pillar countries will initially develop capabilities that can be integrated into each country’s unmanned undersea vehicle platforms. Countries joining the project at a later stage then plan to jointly develop and produce technologies, including next-generation systems, together with the first-pillar countries. The first capabilities are expected to enter service starting in 2027.[ii]
AUKUS’s expansion process is expected to continue solely within the second pillar, through periodically announced projects and a limited cooperation/partnership arrangement. The main reason for this is the protection of sensitive technologies and information security. Every country joining the second-pillar working group brings its own classification systems, export-control regimes, and accreditation standards, which makes technology-transfer rules increasingly complex. AUKUS’s first pillar, by contrast, offers a framework for comprehensive technology sharing among three countries that have different but compatible classification systems.
Every AUKUS member country needs assurance that shared technologies and information will be protected within agreed limits. Under the second pillar, the transfer of sensitive data across allied networks depends on a set of protocols. In this context, Cross-Domain Solutions (CDS) make this possible by enabling controlled, policy-governed data exchange without allowing threats to cross network boundaries. This system sits at the boundary between two networks with different security classifications, inspecting data not only at the packet or protocol level but also at the content level, and determining what may pass through and what must be quarantined. It allows data to move while blocking threats from doing so. This system constitutes a mandatory protocol within AUKUS’s second pillar.
Within the AUKUS framework, it is not only working groups but also collaborative capability-development efforts producing concrete outcomes that continue. Because AUKUS’s second pillar offers a limited cooperation/partnership model, Western powers are struggling to build collective deterrence in the Asia-Pacific. In addition, the extremely strictly enforced International Traffic in Arms Regulations (ITAR) and technology-transfer laws of the US make it difficult to share sensitive defense-industry data even with allies. Among AUKUS members, the United Kingdom in particular considers the cybersecurity infrastructure and legal safeguards against intelligence leaks of candidate countries, such as Japan, to be inadequate. The United Kingdom maintains a fairly strict policy on defense-industry technology transfer and intelligence sharing. The US, meanwhile, is striving to build a broader alliance network under the second pillar. Yet one of the central concerns here is that, as the number of members grows, decision-making processes could be disrupted and reaching consensus could become more difficult.
Canada, Japan, New Zealand, and South Korea, the countries expected to join projects under AUKUS’s second pillar, also wish to preserve their strong economic ties with China. Indeed, these countries’ interest in AUKUS risks provoking a reaction from China, as well as trade disputes and diplomatic pressure. In this respect, the Association of Southeast Asian Nations (ASEAN) and the Pacific Island states calculate that AUKUS’s expansion could trigger an escalation race with China, spark an arms race in the region, and that they themselves would bear the greatest cost of this. Beyond these geopolitical difficulties and constraints, the inadequacies in the national capacities of potential participant countries also deserve attention.
This is because second-pillar technologies are directly dependent on rare earth elements, advanced semiconductors (chips), and specialized titanium/steel alloys. In this regard, dependence on China, which holds the largest share of the world’s rare-earth-processing capacity, continues. Moreover, AUKUS projects (particularly quantum technologies, autonomous swarm systems, and hypersonic defense) require billions of dollars in continuous R&D spending. Beyond this, all three countries face a serious shortage of qualified experts and technical labor in nuclear engineering, cybersecurity, artificial intelligence algorithms, and advanced munitions production. The pact’s expansion risks spreading this already limited pool of skilled human resources even more thinly and disrupting project timelines.
In conclusion, rather than a traditional expansion based on full membership, AUKUS is expected to move forward in the short and medium term through limited, project-based partnerships. Cooperation with countries such as Japan or South Korea is, in particular, expected to increase in advanced technologies under the second pillar, such as artificial intelligence, hypersonic missiles, and quantum technologies. Although AUKUS is a highly functional security pact for balancing China, there remain significant structural and geopolitical obstacles to expanding the alliance’s scope and membership profile.
[i] “AUKUS Partners Advance Submarine Program, Launch First Pillar II Signature Project”, Executive Gov, https://www.executivegov.com/articles/aukus-unveils-first-pillar-ii-project-submarine-cooperation, (Accessed: 08.09.2026).
[ii] “AUKUS announces its first Pillar II signature project”, Squire Patton Boggs, https://www.squirepattonboggs.com/insights/publications/aukus-announces-its-first-pillar-ii-signature-project/, (Accessed: 08.09.2026).
