I'm reading a book on the early years of Vietnam
, starting before WWII. Basically the French period and interval before US intervention. It's very good. I've reached about 1950 and there have past the two time where history could really have been different. These could become interesting SF alternative history candidates. They also illustrate a period generally forgotten in current politics.
The US had a huge anti-colonialist feeling during and after World War II. It wanted all the European colonial empires disbanded. Post war it was obvious that the German and Italian colonies in Africa were to be made independent. US relations with Britain were very tense, with the US position being that the British empire should be peacefully dissolved. The situation for Dutch, Belgian, and French colonies was unclear.
In 1945-46 the US almost declared Indochina independent of France. With the surrender of the Japanese, Vietnam was run by some British troops, the Chinese, and the surrendered Japanese who had accepted Allied command. The British and Japanese had the southern two thirds and the Chinese the northern third. The British made it clear that they wanted to leave, and the Japanese were clearly going to have to leave. The Chinese were extremely unpopular with the Vietnamese, and did not really want a war of occupation when they had internal problems with Mao's army in Manchuria.
The US faced a choice between allowing France to send troops or declaring Indochina independent. This was a very close thing. The Viet Minh had good relationships with US local representatives, who recommended independence. In the end, Truman decided to allow the transport of French troops to Vietnam, (The US ruled the ocean.) This was in contrast to the situation in Indonesia, where there was a similar situation. The Dutch wanted to return and the US said no, Indonesia will be de-colonized and made independent. It could have gone either way. The political forces in the US were very closely balanced and unsure of which way was best.
It came down to fears around Europe. At that point, the UN was a paper organization, Europe was in ruins with widespread starvation. The Marshall plan, NATO, EC, and EU were all in the future. There was fear that Europe would return to chaos and renewed warfare. The argument was that France would disintegrate, the Western alliance break down, and chaos would emerge if the French colonial empire was ended by US edict. Truman decided that de-colonialization could wait, and the risk of chaos with more European warfare was too high. The same considerations for Indonesia were that the Netherlands were less likely to disintegrate and even if they collapsed, the impact on Europe would be acceptable. So Indonesia was freed.
On alternative history would be "what if Vietnam had taken the path of Indonesia?" Would Ho have become similar to Sukarno? Would France have disintegrated into civil war? What would have happened to Europe?
There was a similar point a few years later, with a more difficult US decision, whether to treat Vietnam as a purely internal French problem (with certain bloody defeat and de-colonization) or should the US pick a side. In this period, the French diplomacy was superb and they persuaded Truman and Acheson to support France. This was also quite close in terms of domestic politics, and again European considerations dominated. The French played the anti-communist anti-Stalin card superbly. Then when China fell to Mao, the Soviet Union and China recognized the Viet Minh, and the Communists invaded South Korea the anti-colonialists lost their last hope of keeping Vietnam a purely internal French issue.
From 1950 onward, there were no more points where changing course was easy or likely. Those two were the two where the US almost chose the anti-colonial path.