It's 1990 and twenty-year-old Anthony 'Swoff' Swofford (Gyllenhaal) is a brilliant sniper and part of the elite STA (Surveillance and Target Acquisition) in the US Marines. Trained in Paris Island by drill instructor Staff Sgt. Sykes (Foxx), Swoff strikes up a friendship with platoon rabble-rouser Troy (Sarsgaard) before being packed off to Kuwait when Iraq invades. The young men are hungry for a kill but days turn into weeks and the unit become increasingly disillusioned with their part in a new type of warfare that makes the ordinary foot soldier almost obsolete. With nothing to do but lay around in the sun, play football and worry about what his girlfriend is doing at home, Swoff tries to stay positive but the heat and the business-like way America is conducting the war (the troops are made to sign contracts to ensure that they won't sue if their anti-chemical medicine has side-effects) drains his motivation. Tensions start to rise within the platoon and soon the troops start to turn on each other.
Adapted from Swofford's novel about his tour in the Gulf War, Jarhead wavers between gung-hopro-war propaganda and parody, never making it crystal clear what its stance on war is. The gung-ho aspect comes from the soldiers' determination to right what America did wrong in Vietnam, as the Vietnam vet proudly boarding their homecoming bus, happy that finally his side "did it clean", will testify. Mendes presents the army like a lost generation with no noble cause, making repeated references to other wars (and war movies) - as when the platoon whoops at the helicopter scene from Apocalypse Now, and Swoff shouts in the darkness at a soldier playing The Doors' The End': "That's Vietnam music! Can't we get our own music?" Jarhead is a curious animal, as apart from friendly fire and no sighting of Iraqi troops until almost two hours in, there is not a lot of war in this war movie. Mendes doesn't follow the rules laid down by Kubrick, Coppola and Stone: realism is Jarhead's mission.