Is your implication that Vietnam was a UN-backed war? You may be thinking of Korea. Or is your implication that the US didn't use the UN to fight wars before t

Is your implication that Vietnam was a UN-backed war? You may be thinking of Korea. Or is your implication that the US didn't use the UN to fight wars before the 90's? Because then I think you're forgetting about Korea. Maybe NATO is the org. you're thinking of? Because they did invoke Article 5 for Afghanistan. So I'm not really sure what difference I'm supposed to be seeing.