I've done a few, circa late 1980s to mid 1990s, using Tamiya and Dragon sets. The Tamiya set is undifferentiated, just generic mid 90s or mid 80s American troops, and the Dragon set is specific to US Army Rangers: mid 80s or 90s based on the equipment (it came with a Stinger missile).
Most NATO troops had BDU camoflage, stereotypical Nato Green, Black and Brown camoflage. Helmets were Kevlar with cloth covers, main weapons were M-16 and M-60 (with some others-IDK). That's about all I know. If you want to scratchbuild, I'd start with some of the preexisting kits for troops of the Cold War era first, then go from there.
Good luck on this.