Members of the Five Power Defence Arrangements (FPDA) recently held a series of activities to mark the defence pact's golden jubilee this year.
These ranged from unveiling new stamps to holding an exercise with 2,600 participating troops that culminated in a multinational flypast and naval display off Marina Bay on Oct 18.
Consisting of Britain, Australia, New Zealand, Malaysia and Singapore, the FPDA was formed in 1971 with the aim of safeguarding the external defence of Singapore and Malaysia, amid the withdrawal of British forces from Singapore.
From an initial focus on building air power capabilities, FPDA activities in later decades evolved to include joint exercises and cooperation on non-conventional threats such as piracy and humanitarian aid and disaster relief.
Even as the grouping has updated itself to maintain its relevance over the years, experts said that challenges lie ahead, from the defence capability gap between its members to possible disagreements over its long-term vision.
Why it matters
Unlike binding defence treaties such as Nato, the FPDA is a loose consultative framework between its members.
It commits the five members to consult in the event of an attack or threat against Malaysia or Singapore, an agreement observers said has provided psychological deterrence.
Today, it is part of the patchwork of multilateral arrangements in the region that brings countries together for military exercises and meetings between top leaders, along with others like the Asean Defence Ministers' Meeting-Plus (ADMM-Plus).
The FPDA allows external powers to be involved and provide that balance of power in an Indo-Pacific region that is becoming increasingly contested between the United States and China, said Dr William Choong, a senior fellow at the ISEAS - Yusof Ishak Institute.
Dr Chang Jun Yan, a research fellow at the S. Rajaratnam School of International Studies (RSIS), said that other than providing an opportunity for the non-South-east Asian states to be engaged in the region's security, the FPDA has also allowed confidence-building between Singapore and Malaysia.
Different security groupings in the region, including the FPDA, the Quad and ADMM-Plus, form a complex patchwork for defence diplomacy to happen and to build trust among participants, he added. The Quad, or Quadrilateral Security Dialogue, is a grouping between the United States, its allies Japan and Australia, and security partner India.
Assistant Professor Sarah Teo, coordinator of the Regional Security Architecture Programme at RSIS, said the FPDA's profile as the "quiet achiever" has worked to its advantage.
"For instance, there has been comparably little regional concern expressed about the FPDA vis-a-vis other platforms, in the context of Sino-US rivalry or challenges to Asean centrality," she said.
What lies ahead
At a meeting between the countries' defence ministers in October - the FPDA's pinnacle decision-making platform - three principles were approved to guide the FPDA's course for the next 10 years.
These are: How the FPDA should not deviate from its remit to contribute to the external defence of Malaysia and Singapore; how it should continually evolve to ensure its relevance; and maintaining its portrayal as a defensive arrangement to provide reassurance.
The defence ministers also agreed for the FPDA to focus on, among other things, continuing high-end military drills with new assets and introducing cyber security progressively into its exercises.
Dr Chang said the key challenge of the FPDA in the years ahead remains the same as when it marked its 40th anniversary - being able to maintain its relevance in a changing security climate.
It stands in good stead to do so, he said, due to its flexibility and consultative nature. But this means disagreements between its member states on the way forward may also fray the security arrangement, much like Asean, he added.
Senior fellow for Asia-Pacific Security Euan Graham at the International Institute for Strategic Studies said another key issue was how Malaysia and New Zealand lag behind the other member countries in modernising their defence forces.
One encouraging sign is how countries have stepped up their publicity for FPDA, he said.
The set of commemorative stamps issued by Singapore Post earlier this month shows efforts to educate the public about the FPDA.
Dr Graham said: "I think that is a more subtle challenge because in this era, you can't just leave defence to the military professionals; you also need political buy-in."
He said the FPDA should not be too ambitious in changing its mission or growing its membership.
"The fact that it has lasted for 50 years tells its own story - you don't survive unless you are useful. It is unique in South-east Asia as a defence multilateral organisation."