Strengthening the Line: Australia and the Philippines Deepen Defence Ties Amid Rising Tensions

Piper Stock | Indo-Pacific Fellow

Image sourced from Presidential Communications Office (PCO) via Wikimedia

As strategic rivalry intensifies in the Indo-Pacific, defence cooperation between Australia and the Philippines is taking on increasing strategic relevance. At the 2nd Philippines-Australia Defence Ministers meeting, the message was clear: both countries are deepening defence cooperation in response to intensifying strategic competition, rapid military build-up lacking transparency, and intensifying maritime coercion in the South China Sea.

The meeting reaffirmed defence cooperation as a central pillar of the Philippines-Australia Strategic Partnership. But beyond diplomatic pleasantries, it signalled a significant shift. Australia and the Philippines announced plans to finalise a new defence agreement next year, allowing Australian forces access to Philippine military bases and deepening joint military operations. For both nations, this marks an evolution from dialogue to deterrence.

From Strategic Alignment to Strategic Necessity

Australia and the Philippines share more than geographic proximity; they share a history of strategic alignment. Both are long-standing treaty allies of the United States (US), with the Philippines’ alignment anchored in its 1951 Mutual Defence Treaty with the US, which provides a formal security guarantee shared by only a small number of states in the Indo-Pacific region. Over the past decade, China’s island-building campaign in the South China Sea has transformed reefs into fortified outposts complete with airstrips, radar systems and missile sites. The militarisation of features such as Woody Island and parts of the Spratly archipelago has alarmed regional actors, particularly the Philippines, which continues to face repeated confrontations with Chinese vessels near the Second Thomas Shoal within its Exclusive Economic Zone.

The US has reaffirmed that the Mutual Defence Treaty applies to Philippine forces and vessels in the South China Sea, while Japan has increased its engagement with the Philippines through defence equipment and training. Australia is now joining this circle of cooperation, reflecting shared concern over China’s unilateral actions that are inconsistent with its obligations under the United Nations Convention on the Law of the Sea (UNCLOS). The Philippines’ strategic location at the junction of the South China Sea and the Western Pacific, combined with its frontline role in maritime disputes, makes it central to regional stability and a compelling partner for Australia in strengthening maritime security and regional resilience.

Deterrence Without Escalation

From the Philippines perspective, the defence partnership is intended to deliver tangible deterrence rather than symbolic reassurance. Enhanced cooperation is designed to improve combined operational capability through more frequent joint exercises, greater interoperability, and access to modern defence infrastructure. These measures aim to raise the costs of coercive behaviour while remaining below the threshold of escalation.

For Australia, the partnership reflects a strategic response to regional instability. Australia increasingly sees the security of Southeast Asian partners as integral to broader Indo-Pacific stability. A more capable Philippines strengthens collective resilience and reinforces the principle that maritime disputes should be managed according to international law. Yet the partnership has limits. It is not designed to decisively alter the regional balance of power or deter China unilaterally. Its value lies in signalling coordination and resolve, embedding bilateral cooperation within a wider network of partnerships that collectively complicate coercive strategies.

Regional Legitimacy and Australia’s Strategic Reputation

The deepening partnership has drawn regional attention. China has criticised expanded defence cooperation and joint maritime activities, framing them as destabilising and externally driven. While escalation remains unlikely, increased surveillance, diplomatic pressure, and grey-zone tactics directed primarily at the Philippines are probable. China’s focus on the Philippines rather than Australia highlights the asymmetry in perceived threat and influence, with the Philippines viewed as a frontline claimant in direct maritime disputes and Australia as a more distant, non-claimant partner.

Across Southeast Asia, reactions are more nuanced. Some states, including Vietnam and Singapore, view the partnership as a necessary response to rising coercion in the South China Sea, while others including Laos and Cambodia remain wary of increased militarisation and entanglement in major power rivalries. For Australia, this underscores the challenge of balancing deterrence with respect for regional autonomy and Association of Southeast Asian Nations (ASEAN) centrality, and Australia’s standing in the region. For partners such as Japan and the United States, the partnership reinforces Australia’s reputation as a dependable security contributor.

Walking the Line Ahead

Looking ahead, the sustainability of the Philippines-Australia Strategic Partnership will depend on balancing deterrence with diplomacy. While enhanced defence cooperation strengthens resilience and raises the costs of coercion, both countries remain conscious of China’s role as a major economic partner. For Australia, this balance is particularly consequential: its security, trade flows, and strategic credibility that are deeply tied to stability in the South China Sea and to the preservation of international law, including freedom of navigation and respect for the UNCLOS. Avoiding a zero-sum approach while maintaining strategic consistency across political cycles will therefore be essential to ensure that deeper security ties reinforce, rather than undermine, regional order.

As the Indo-Pacific enters a decisive decade, the partnership reflects a broader shift from cautious observation to active coordination among middle powers. Since the elevation of relations to a Strategic Partnership in September 2023, Australia and the Philippines have moved beyond traditional diplomacy towards sustained strategic and defence cooperation. This underscores the reality that peace is unlikely to be preserved through diplomacy alone, yet deterrence must be carefully calibrated to avoid exacerbating tensions. In navigating these trade-offs, the Philippines-Australia partnership illustrates how states can manage power asymmetries, alliance politics, and regional expectations while defending international law and contributing to long-term regional stability.

Piper is a fourth-year Bachelor of Laws and International Relations student at Griffith University. She currently works as a Federal Electorate Officer in the Australian Parliament, where she undertakes policy research, drafts parliamentary correspondence, and supports constituents on a range of federal matters. She also has professional experience in the legal sector as a Legal Administrator. Piper is actively engaged in leadership and public service. She is a Board Member of the Griffith University Student Guild, a Gold Coast Mayor’s Student Ambassador, and a mentor for Political Science and International Relations students at Griffith University. She has also been recognised with the Griffith Business Leadership Award. Through this fellowship, Piper hopes to combine her strong interest in the Indo-Pacific region with her professional experience to explore how dome

stic policy, diplomacy, and regional cooperation intersect in shaping Australia’s engagement with its nearest neighbours.

Disclaimer: The views and opinions expressed in this article are those of the author, and do not necessarily reflect the views and opinions of Young Australians in International Affairs. AI tools were used by this author for grammar checks and idea refinement, but all content is original, and no plagiarism has been used in the preparation of this article.