This volume has its genesis in a conference co-organized by the S. Rajaratnam School of International Studies (RSIS) and the Institute of Southeast Asian Studies (ISEAS) in March 2011 entitled the “Five Power Defence Arrangements at Forty”. The conference celebrated the FPDA's contribution to regional security over the last four decades and explored its response to changes in the strategic environment.

The FPDA was set up in 1971 at a time of considerable geopolitical uncertainty. It was not just Singapore-Malaysian relations that were touchy at the time, after the Separation of 1965. The Association of Southeast Asian Nations (ASEAN) was also new, having been established only a few years earlier, and its members were still in the early stages of building confidence to work together to face the common security challenge of the time, namely communism. The war in Vietnam was not going well for the non-communist side, and a US withdrawal seemed inevitable at some point. US President Richard Nixon had already announced the Guam Doctrine in 1969, according to which American involvement in wars on the Asian mainland would be limited to a supportive role while allies and friends would be expected to bear the main burden of defending themselves by providing ground troops.

In 1971, nobody could tell how long the FPDA would last. Sceptics dismissed it as an impotent successor to the Anglo-Malaysian Defence Agreement (AMDA), a mere figleaf to cover the British military withdrawal from the region. They were proved wrong, given the fact that it has lasted 40 years and its five members continue to attest to its ongoing relevance. It has proved to be a valuable confidence-maintaining mechanism and its built-in flexibility allows it to adapt to a changing security environment.

Since its inception in 1971, the FPDA has played a critical confidence- building role in Singapore-Malaysian relations. Before its formation, the Malaysian and Singaporean armed forces had long been comfortable with working with British, Australian and New Zealand forces.