In 1945-1985 NZ was involved militarily in Asia. The main reason was the Canberra pact of 1944. The main conflicts NZ was involved in were Korea (1950-1953), Malaysia (1960-1966), and Vietnam (1965-1972).
One of the reasons NZ was involved in Asia was the Canberra pact, signed in 1944. It was actually an illegal pact, as NZ hadn't adopted the Statute of Westminster that gave them control over their external affairs. The Canberra pact was signed with Australia, because they (Australia and NZ) were afraid that the Allies would forget or ignore them in post-war settlements. In the Canberra pact NZ and Australia pledged to consult with each other about goings-on in the region. It also said they would oppose military installations and build a council that would promote economical and social growth.
NZ believed in "Collective Security." This meant that they were involved in the United Nations and the Commonwealth. Some of the documents that NZ signed that committed her to the Asian conflicts were ANZAM where Australia, Britain and NZ planed defense for Malaya. ANZAM was replaced by the Five Power Defence Arrangement in 1971. The ANZUS treaty of 1951 was between Australia, NZ and USA. And the SEATO agreement was the SouthEast Asia Treaty Organization, signed in 1954 with Australia, Britain, France, Pakistan, Philippines, Thailand, and USA.
NZ was involved in Korea after North Korea invaded South in 1950. The UN decided this was aggressive action and sent in troops. NZ sent K-Force troops, artillery, airforce, infantry and 6 frigates. 33 men were killed and 79 wounded.
In Malaysia, NZ troops stopped communist aggression as part of ANZAM. They were stationed in Singapore. In 1963 the federation of Malaysia was formed and troops stayed to look after the new nation. Indonesian guerillas had running battles with troops. This lasted until 1966 when Indonesia withdrew her troops.