[Legbreaker]

That could work, but we'd still be left with the high probability of those troops being recalled home as soon as the war with Indonesia heated up. Might be a few advisors left (similar to "the team" in Vietnam), but I can't see whole units.
Besides, it's a war between China and the USSR to begin with, the US appear to have been involved in that area mainly because they already had units in South Korea. I doubt ANYONE would have considered actually entering combat against the other superpower in support of a communist country. Weapons and supplies through an intermediary yes, but troops?

This of course raises the question of why would the Soviets assist the North Koreans in their attack on the South? From deployment dates of various units, and subsequent histories, we can see the attack did not occur until 1997, months after action commenced in Europe. My thoughts are it was an attempt to knock the US troops out of Asia so the Soviet units could be redeployed westward and help stop the Nato advance across eastern Europe.

Any way I look at it, I can't justify Western nations other than the Koreans and US in Korea without United Nations involvement. The UN headquarters were not destroyed until late 1997 when New York was nuked, so it is possible (but I doubt it). The UN may even have relocated itself out of a belligerent country when the nukes were first used. Perhaps the UN still exists in a rather impotent way in say Australia, New Zealand, South Africa or maybe Argentina? A hell of a lot of civilians fled the cities in panic, so I can't see why the UN wouldn't have "temporarily" relocated too...