The U.S. wiki doesn't mention Veitnam.

I just briefly skimmed it over, it mentions World War 1 and 2 but not Veitnam (which they lost). Does anyone find that odd?

It could be argued that the Vietnam was as important as the world wars since it was an action to nip aggressive activities through proxies by Moscow which if succeeded quickly and easily could have lead to more aggressive activities and it bought Thailand enough time to dig in militarily, economically, politically and socially to defend itself from communist insurfents.

I would say America won the Vietnam war. We succesfully defended South Vietnam while we were there and it was clear to the world we only left because some pot smoking hippies lifted a finger and we happen to actually be an egalitarian democracy not some evil capitalist plutocracy.