Among American ones the choice is obvious, smth like:
Platoon
Full Metal Jacket
Apocalypse Now
Saving Private Ryan etc., all classics, though I tend to dislike the latter one, still classic. Other hyped movies like Pearl Harbor and Enemy at the Gates are garbage imo.
As for the more obsucre ones, here're couple of Soviet movies that are good:
Hussar Ballad:
http://www.youtube.com/movie?v=hqjgS0hdrEc
A comedy musicial about Patriotic War of 1812, aka Napoleon invasion, hilarious, though a bit old-fashined by modern standards, started the series of jokes about poruchik Rzhevsky.
They Fought for Their Land:
http://www.youtube.com/movie?v=obBpLyIgbww
http://www.youtube.com/watch?v=jWwVex6Y-tg
There're shitload of Soviet WW2 movies, some are good, some are very good, but this one probably the best. War drama set during early stage of Great Patriotic War, aka Hitler invasion, slow paced and not without patriotic sentiment, which though doesn't spoil it a bit. Movie based on Sholokhov unfinished novel of the same name, shame it was never finished, could have been definitive work of its kind.
As for the Soviet movies about Vietnam... not much, the best I can remember is Coordinates of Death (Tọa độ chết in Vietnamese), overly propagandistic, but at least copters used by Americans to kill civilians are actual Hueys, not the fake Hind (was it Stallion?) in the Rambo 2 :D. Watch it if you hate America:
http://www.youtube.com/watch?v=x64T3vI6RnY
