The military is featured in GTA 2, GTA III, GTA Vice City, GTA San Andreas, GTA Chinatown Wars and Grand Theft Auto V. In GTA games are the armed forces of the USA, comprising mostly of the Army, but also with air and naval bases. The army themselves don't appear in Grand Theft Auto IV, because it enhances realism - the army would not be sent to kill one person, and because the Posse Comitatus Act prohibits the use of federal military personnel and units of the National Guard under federal authority from acting in a law enforcement capacity within the United States, except where expressly authorized by the Constitution or Congress. The army is replaced somewhat by NOOSE. The military is also important in many missions throughout the series, such as Sir, Yes Sir!, Black Project, Green Goo, Up, Up and Away!, Vertical Bird, Robbing Uncle Sam and Over the Top.
Grand Theft Auto 2
After getting a six star wanted level the military replace the police. Pedestrians disappear and normal cars become a rare sight. The soldiers in GTA 2 are armed with machine guns and shots can kill the player and destroy cars. The military use different vehicles much as the Barracks OL and the Rhino. The military has its base in residential district but the base is totally inaccessible, but there is a small base in the industrial district to which the mission can be accessed at Army Base Alert!.
Grand Theft Auto III era
After the player gains six stars in a GTA III Era game, the army will begin to chase the player. On the ground, two military vehicles are used to kill the player; the Barracks OL, which is used for troop transport, and the Rhino tank. The soldiers themselves are always well armed with weapons that will often make short work of the player and most vehicles.
Members of the military behave as a gang in Vice City despite not really being one and will attack the player if spotted on military territory, unless in a Cop uniform. They will also set up roadblocks comprised of the Barracks OL with soldiers armed with M16's in GTA III, M4's (in Fort Baxter Air Base) and MP5's (during a 6-star wanted level), and M4 Carbines in every other GTA III Era game. These aren't as lethal as those of the FBI since there could be two FBI vehicles taking up one road with at least eight agents. But seeing as how the Barracks takes up the space of one road they can be broken through although the MP5s still pose an extreme threat.
A strange thing is that soldiers in the Fort Baxter Air Base never participate in law enforcement activity; if the player is wearing a police uniform or army fatigues and enters the base with a wanted level; only the law enforcement officers that enter from outside will try killing the player.
Grand Theft Auto: Chinatown Wars
After gaining six stars, the Rhino and occasional on-foot military soldier will appear. Soldiers are armed with AK-47s at all times. While encountering an occupied Rhino, the player cannot hijack the occupied Rhino. However, there are two ways the Rhino will react depending if the player is on foot or in a vehicle. If the player is in a vehicle, the Rhino will immediately fire at the player's vehicle setting it aflame (but not blow it up giving the chance for the player to bail out and save his or her life). However, if the player is on foot, the Rhino will reluctantly fire giving the player ample time to escape. The very slow speed of the Rhino makes it easy for the player to outrun it on foot. The Rhino will eventually fire at the player if the player stays in range on foot for too long. A direct hit usually kills the player unless the player has full health and full armour, but will reduce the health to roughly 25% and armour to 0%. The same goes for the Destroyer when the player enters the water.
- Fort Baxter Air Base in Vice City Mainland, Vice City.
- United States National Guard Depot in Ocean Docks, Los Santos, San Andreas.
- Easter Basin Naval Station in San Fierro, San Andreas.
- Area 69 in Bone County, San Andreas.
- K.A.C.C. Military Aviation Fuel Depot in Las Venturas, San Andreas.
- Fort Zancudo near Mount Josiah, San Andreas
- Barracks OL
- Jetpack (prototype experiment, stolen by Carl Johnson in 1992)
- Land Roamer, (Armed)
- Mesa Grande
- Tiger Tank, (possibly an ex-German tank from World War 2)
- In Grand Theft Auto: Vice City, the soldiers at the Fort Baxter Air Base are considered to be part of the Streetwannabe's gang.
- In the GTA III Era the Rhino tank (which chases the player at six stars) does not fire it's main gun. However, in Grand Theft Auto: Chinatown Wars the Rhino is programmed to use its turret to full effect, blasting the player into oblivion.
- The Vice City National Guard soldiers strangely seem to wear fatigues similar to the present day German Army fatigues.
- The Army soldiers are very dangerous. An example of this can be easily told when the player does the mini gun Rampage to kill all the nearby gang members. If a group of army men see one of the gang members they will instead open fire on sight leaving no time for the specific gang to retaliate back.