The main arguments for it being a pro military and pro war movie is that the Bugs ARE attacking and that if humanity wants to survive, they will have to fight. Then, while most people do die, the movie ends with a major victory that looks like it may help save humanity.
I don't really think you can argue those points away to claim its an anti military/war movie. The movie would have needed for humanity to have attacked the bugs first, starting the war; or at the least having had most everyone die for no reason, without making a shred of progress in the war effort.
I mean, they were fighting to save our entire species, and the two most vocal people in the entire movie (Ricos parents) that were against the military machine were some of the first people to die in the movie.