I was #96 in the 1973 draft lottery. So I know this history more than almost anyone and need no ex-marine to teach me. I protested against the Vietnam War and read Chomsky's book on Vietnam in 1975. Here's the first of a 3 part series on Vietnam: https://medium.com/lessons-from-history/mythbusting-tour-vietnam-a-war-with-no-winner-part-1-393f013bff01 . America's transition from empire demolition against Japan to empire building in the summer of 1945 was virtually instantaneous, to the chagrin of many OSS agents in China and Indochina. That's what Graham Greene's The Quiet American and Stanley Karnow's books on Vietnam are all about.

Here's a simple geopolitical fact: America's best ally in SE Asia is now....Vietnam. Smaller states bordering historically oppressive overbearing neighbors need distant superpowers to ally with. The choice is not between good and bad, but between bad and worse. US allies in SE Asia and eastern Europe know this and therefore ally with the American hegemon precisely because its two oceans make territorial conquest pointless. America's new form of informal empire is preferable to the older kind practiced by Russia and China. Good vs bad is not on the menu of the History Restaurant.