That would be 40-50 years ago, if you refer to Viet Nam.
30 years ago it was the year 1981 ...
We are getting old, are we not?
EDIT:
Is it just me or is the UN embarking on yet another disturbing facet of globalization? Libya is a curious operation, to date. If nothing else, it lets the French show that they can wave their willies as well as any other power. For that, we thank our French friends.
But let's look at this with as neutral a view as we can.
A sovereign nation state and UN member (regardless of how strangely led, or how culturally backward) is having a civil war. The UN cannot iron out a cease fire, nor a peace agreement, nor get the sides to stop shooting (a common failing on the part of the UN) so it chooses sides and asks various member states to offer up war waging capability in order to back a preferred side with blood and iron.
What member state is pleased with this turn of events?
To paraphrase the lyrics from a Hollywood soundtrack ...
Watcha gonna do when they come for you?
One of these days, it's gonna be the Chinese, rather than the French, waving their willies about ...
Twenty years ago, I was a UN fan. Since about 1992, as I began to understand the distrust of the UN at local levels (Somalia being a beginning, the curious case of Specialist Michael New being another, the cock-ups Ritter exposed over the cease fire agreements,1991 Gulf War, the UN brushed aside by NATO to bomb Serbia over Kosovo in 1999).
I find my taste for that level of multinational collective security to have declined sharply.
What really annoys me, however, is the gutlessness. Note how the UN cut and ran, tail between legs, along with some of its donor nations, after the UN HQ in Baghdad was hit with a bomb in August 2003. Predictable, if you watched UN shenanigans in Somalia, eh?
What nation actually benefits from being a UN member?
At what point does the cost benefit curve knee, or diverge?
How did Iraq benefit from being a UN member?
How does Lebanon?
I ask this at the collective security level, not the health and trade level, where the UN IMO does yeoman work.