Here's the idea -- take a TL without US Vietnam War; how likely, in this scenario, is the US getting involved in a counter-insurgency quagmire somewhere else (what OTL calls "another Vietnam"), and where could it plausibly happen?
Examples of TLs without Vietnam:
*Ho Chih Mihn becomes a US ally (maybe via Pres. Wallace, or something)
*Chiang Kai Shek wins the civil wars in China, and intervenes directly in Ho Chih Mihn's country
*JFK isn't shot, pulls out advisors following his re-election