Anti-war films typically argue that war is futile, unjust, a loss for all involved, only serves to benefit few in society (usually an elite or ruling class, or the state), makes people do or support things they normally would not (such as homicide or discrimination), is extremely costly both in money and lives, or is otherwise undesirable for those fighting it, the target audience, or everyone in general.
Though many anti-war films make this negative depiction explicit and clear for the audience to understand, some are more subtle in delivering their anti-war messaging (such as making the ostensibly good side as brutal as their enemies), or may use parody and black comedy to satirize wars and conflicts.
[1] Several filmmakers and critics have been quoted as stating that "there is no such thing as an anti-war film",[1][2] first attributed to François Truffaut.
This school of criticism argues that cinema is inherently "an inadequate medium through which to convey the horrors of conflict" and that any such portrayal of combat and violence will always glorify warfare on some level, even if only through the death of the author.
[1] Supposedly failed anti-war films in this regard include Full Metal Jacket and Saving Private Ryan; The former was decried as "another goddamn recruiting film" by Samuel Fuller, while the latter was criticized by Toby Miller as legitimizing the United States as the military savior of the world.