The collapse of colonialism in South-East Asia, where three empires, British, French and Dutch, had sprawled untidily over the map, left the area without regional coherence in a clear need for it. The fall of Saigon in 1975, at the end of the second Indochinese war, marked the end of the brief period of American dominance and, apparently, of external intervention. The United States, scarred by the internal divisions caused by the costly and ultimately unsuccessful war in Vietnam, turned with huge relief away from the commitment of American troops on land in South-East Asia towards a purely maritime strategy for the region, based on the islands and island states of the Pacific.
There was a price to pay for this: it was no longer possible to exercise influence over events on land in the area. Governments were toppled or put in place by small, hard, wiry men crossing land frontiers, not by the actions of ships at sea or by unscrewing the nose cones of missiles. This had to be accepted. Domestic politics would stand nothing more. This was not to say that the United States was leaving Asia. Far from it; the US had every intention of remaining a power in the Pacific basin, the fastest growing economic area in the world. America's centre of gravity, however, would henceforward be in North-East Asia, built around the security link with Japan and, as it turned out later, a growing understanding with China. The naval and air bases in the Philippines would still be needed for US maritime strategy. Washington hastened to renew the leases for them. Manila was initially hesitant, not merely to drive a hard bargain but because the waning of American strength and influence was creating a climate of caution. But Vietnamese actions in Indochina soon put an end to regional hopes for stability and the other ASEAN (Association of South-East Asian Nations) states pressed the Philippines to sign, to enable the United States to keep a strong military presence in the area. South-East Asia was looking to Washington once more; the countries needed powerful friends again. In January 1979 the new agreements for American use of the Philippine bases were concluded.
It was the men in Hanoi that brought all this about. The North Vietnamese had emerged in heroic guise from the longest and bloodiest war of independence that South-East Asia had seen, unifying a country which now had military power far greater than its neighbours, allied to a fanatical determination to go on using it if need be, regardless of the opposition. In the aftermath of the war the ASEAN hope was that the Vietnamese energies would be channelled into uniting the hitherto divided nation and into rebuilding the war-torn economy. The fear was that communist or nationalist fervour would prevail instead, with Hanoi pursuing the aim of controlling the whole of Indochina, the long-held ambition of Ho Chi Minh. And then what? Further into South-East Asia?
The ASEAN leaders put out friendly feelers, making clear their desire for stability and their willingness to encourage and help with economic consolidation. Japan offered economic aid to Hanoi. This was perhaps the best way of drawing Vietnam towards peace and the West and away from the Soviet Union, now Hanoi's principal patron. The United States was unhappy at the idea of rewarding the intransigent in this way, at least so soon, but itself none the less conducted discreet negotiations with Hanoi to pave the way towards normal relations when the wounds had healed a little. Vietnam seemed willing to contemplate this, but all stopped when in November 1978 it concluded a treaty with the Soviet Union and shortly afterwards invaded Kampuchea (Cambodia), overthrowing the admittedly hateful and genocidal regime of Pol Pot and installing its own puppet, Heng Samrin.
Conflict in South-East Asia had thus broken out again, heavily supported, indeed only made possible, by the military assistance given to Vietnam by the Soviet Union. China, traditionally sensitive to Vietnamese ambitions, soon reacted in support of Pol Pot and in February 1979 briefly invaded Vietnam. While this attack certainly exposed China's military inadequacies, not least to Peking, it none the less imposed great costs on Hanoi, drawing a large part of Vietnamese military strength northwards to the frontier regions, where it was tied thereafter by the threat of renewed hostilities.