Between 1962 and 1966 Indonesia and Malaysia fought a small, undeclared war which came to involve troops from Australia, New Zealand, and Britain. The conflict resulted from Indonesia's President Sukarno's belief that the creation of the Federation of Malaysia, which became official in September 1963, represented a British attempt to maintain colonial rule behind the cloak of independence granted to its former colonial possessions in south-east Asia.
The term "Confrontation" was coined by Indonesia's Foreign Minister, Dr Subandrio, in January 1963, and has come to refer to Indonesia's efforts at that time to destabilise the new federation, with a view to breaking it up. The actual war began when Indonesia launched a series of cross-border raids into Malaysian territory in early 1963.
The antagonism that gave rise to Confrontation was already apparent in December 1962, when a small party of armed insurgents, with Indonesian backing, attempted to seize power in the independent enclave of Brunei, only to be defeated by British troops from Singapore. By early 1963 military activity had increased along the Indonesian side of the border in Borneo, as small parties of armed men began infiltrating Malaysian territory on propaganda and sabotage missions. These cross-border raids, carried out by Indonesian "volunteers", continued throughout 1963. By 1964 Indonesian regular army units had also become involved.