Australia and New Zealand (ANZ) were among the earliest of ASEAN's external partners. But their interests in the Southeast Asian region ante-dated the formation of the regional association. What is noteworthy about those interests was that they were defined largely in the context of ANZ's old Commonwealth links with Britain on the one hand and their post-World War II alliance relationships with the United States (ANZUS and SEATO) on the other. The result of these derived relationships was firstly the absence of a coherent regional anchorage for ANZ foreign policy interests and secondly preponderant emphasis on the military dimensions in their relationship towards Southeast Asia.

Before World War II, Australia and even less so in the case of New Zealand (which had little historical context to its relationship with other Southeast Asian countries), thought little about the region per se but looked primarily towards Britain as the major point of reference vis-à-vis the British-ruled territories of Malaya and Singapore as a theatre of operation. ANZ troops served alongside Britain's in the defence of the Malayan region during World War II. The Japanese invasion and occupation of Southeast Asia and Britain's failure to defend Malaya, Singapore and the then Dutch East Indies, heightened Australia's awareness of its proximity to the region and “the threat from the North” — a security syndrome which haunted policy planners in Canberra in ensuing years when new conflicts caught up with the emergence of newly independent states in the post-colonial period. West rian, the Vietnam War, Konfrontasi, and East Timor were some of the more vexing challenges that complicated particularly Australia's relations with regional states “to the North“.

With the advent of the Cold War the legacy of ANZ's Commonwealth links to Britain in the Malayan area was translated into participation in the war against Communist insurgency. Malayan independence in 1957 further transformed the status and nature of such defence linkages and ANZ became associated with the Anglo-Malayan Defence Agreement (AMDA), which was Britain's continued guarantee to the external defence of Malaya and later Malaysia as well as Singapore.