Writing in The Strategist ^[1] three years ago, I made the then-provocative assertion that the Philippines could be Australia’s most important defence partner in Southeast Asia. Fast forward to 2025, and the Philippines is now more strategically entwined with Australia than any other Southeast Asian country, while in political terms, Canberra could even be considered more closely aligned with Manila than it is with Washington’s current management. Australia’s largest overseas defence exercise of 2025 took place in the Philippines for a reason.

An ASPI special report ^[2] released today, Allies Entwined: Australia’s Strategic Convergence with the Philippines, analyses the factors that have brought about an unparalleled strategic convergence between Australia and the Philippines, including consideration of Australia’s strategic interests in the Philippines. It explains why a political window has also opened in Manila for institutionalising the Philippines’ international defence partnerships and further assesses a major joint defence exercise—Alon 2025, conducted in the Philippines in August—in light of a planned upgrade to the defence relationship with Australia. Finally, it offers policy recommendations to both governments for furthering defence ties.

In August, against the backdrop of Alon 2025, the Australian and Philippine defence ministers committed to deepening defence cooperation. Exactly what form this upgrade will take remains in play. Alon was noteworthy not simply as Australia’s largest overseas drill this year but as a muscular projection of Australian Defence Force combat assets into a key location in what US strategists commonly refer to as the First Island Chain, which hinders China’s access to the Pacific and Indian oceans.

Since 2017, Australia’s defence relationship with the Philippines has evolved considerably to become Manila’s closest security relationship after that with the United States, which has also recently revitalised its bilateral treaty alliance with the Philippines. While Canberra and Manila are not formal bilateral allies—at least not yet—Australia has independent reasons to be invested in the security of the Philippines beyond its importance to US strategy in the Indo-Pacific. The Philippines contains vital terrain in maritime Southeast Asia. It is also worth defending, in normative terms, as a democracy of approximately 115 million people whose sovereignty is being challenged by an expansionist authoritarian power, China. The positional importance of the Philippines coupled with its revived treaty alliance with the US also make it pivotal to deterring aggression against Taiwan. By defending the Philippines, Australia can contribute to defending Taiwan.

Closer alignment between Australia and the Philippines reflects shared threat perceptions towards China, which has fixed the Philippines in its strategic crosshairs through daily harassment in the South China Sea and other forms of coercion. US regional allies are also cross-bracing their security partnerships, in part, because of shared doubts about the political willingness of Washington to honour its treaty defence guarantees.

A military contribution to the defence of the Philippines against external aggression means bearing additional strategic risk for Australia. But as the most likely scenario to involve the ADF in a conflict between China and the US, there are sound reasons for Canberra to do so, including defending regional order and a democracy under direct threat.

Although the strategic implications of a closer alignment between Australia and the Philippines are consequential, this has not filtered down to Australia’s wider strategic policy community. One of the purposes of this report is to bring greater knowledge of this increasingly important relationship for Canberra to a wider audience.

The report offers a number of wide-ranging policy recommendations. Among these are that Australia and the Philippines should jointly:

—Institutionalise bilateral defence cooperation as far as possible before President Ferdinand Marcos Jr leaves office in June 2028. The next step would be to upgrade the existing bilateral memorandum of understanding to an executive-level agreement, concluded and signed by the two heads of government, in 2026.

—Scope the potential for Japan to participate in more military exercises in the Philippines, including the next iteration of Exercise Alon, in 2027. Australia, Japan, the Philippines and the US should intensify efforts to harmonise their interlinking acquisition and cross-servicing, visiting forces and logistical support agreements, to identify synergies and minimise unnecessary duplication.

Australia should:

—Do more to steer the strategic partnership on the foreign policy side, including encouraging Southeast Asian countries to show greater diplomatic and practical support for Manila whenever it faces intimidation and coercion from Beijing.

—Explore options for prepositioning defence equipment and stores in the Philippines, to reduce the cost of future exercise deployments from Australia and to facilitate a short-notice contingency response.

—Propose military medicine and defence health as an additional focus area for bilateral defence cooperation, with a view to boosting the resilience of the Philippines in this area.

The Philippines should:

—Adopt greater consistency and discipline in its strategic communications towards China, and demonstrate its willingness to deploy military assets near disputed features for deterrence purposes.

—Expand its own defence infrastructure, buying back facilities previously sold to the civilian sector. Funding priorities for territorial defence should include improving the country’s capacity to support its armed forces and to host foreign forces.