Since i really like them, here's a good war movies list.
This is some of my favourite Modern War Movies that pop ups in my mind:filmed after the 1990, that might interest you more if you are young or not that much into war movies or old cinema.
The Pacific and Band of Brothers. Both miniseries with 10 episodes from Tom Hanks and Spielberg (that they also did the awesome but much less accurate Saving Private Ryan) they are more kolossals then tv series so i put in the list.
Both are in ww2, The pacific is Marines vs Japanese, Band of Brothers is mainly Americans vs Germans.
They are really awesome, even if you are not into war films check them.
Letters From Iwo Jima, from clint eastwood. I suggest watching it with japan audio.
The last Samurai. Beautiful film and the battles of samurais against an european like army are pure awesomness.
El Alamein - The Line of Fire (El Alamein - La linea del fuoco). Cool italian war movie on our poor soldiers at the El-Alamein battle. It's well made and i think watching the war from the italian prospective would be interesting for foreigners too, it doesn't happen often
Black Hawk Down. Somalia 1993, 2 hours of madness and epic gun fights, it feels like a videogame but it's quite accurate about what really happened, wich is scary.
Enemy At the Gates. A western movie athmosfere, but with scoped rifles and stalingrad instead of some american desert. Cool to watch.
On the Iraq war there is
Redacted and
The Hurt Locker that won the 2010 oscar for best film
Downfall. German movie on the last days of einstein and the battle of Berlin.
Thin Red Line. American Movie on the guadalcanal (pacific theatre) in ww2.
Stalingrad German war movie of the '90
Gomorrah. Italian movie about the war beetween Cammorra(neapolis Mafia) and Scissionisti (Separatists) .
That isn't classified as a war movie, but it actually talks about a war with thousands deaths, and in the film there is a lot of beating and gunfights. And the film itself is awesome, it reminds those '50 and '60 neorealist italian movies, but with a touch of hollywood modern style.