This paper discusses the evolving Southeast Asian security architecture by focusing on the role of a “mini-lateral” defence coalition, the Five Power Defence Arrangements (FPDA). Examined from the Singaporean and Malaysian points of view, the paper investigates whether the FPDA complements or is being gradually supplanted by other regional security instruments in Southeast Asia. The other mechanisms covered in the paper include the activities undertaken by Malaysia and Singapore with the United States bilaterally, mini-laterally with Indonesia through the Malacca Strait Patrol (MSP), and multilaterally through the emerging ASEAN Defence Ministers’ Meeting (ADMM) process. The overall argument of the paper is that for Malaysia and Singapore the FPDA continues to complement these bilateral, mini-lateral and multilateral security instruments, yet each in very different ways. In that sense, the FPDA plays a clear, although limited, role in the Southeast Asian security architecture.