I think Hurt Locker is the only movie that no Freeper can reach a consensus if it was anti war or not. Lots of threads on it, and there’s no one major view of it.
Most war films are "anti-war" in the sense they show horrible things that happen in war. In the good ones that's just being realistic. War is bad. But what most people think an "anti-war film" means is that it questions the rightness of the specific war being depicted. I can't think of anything in Hurt Locker that did that.