American soldier (Operation: Anchorage)

American Soldiers are the backbone of the U.S. Army in Fallout 3's Operation: Anchorage DLC.

American Soldier
American Soldiers wear Winterized Combat Armor and use R91 Assault Rifles.

American Sniper
American Snipers wear Winterized Combat Armor. They utilize a Sniper Rifle.

American Inferno Unit
American Inferno Units wear Winterized Combat Armor and carry a Flamer.

American Launcher
American Launchers wear Winterized Combat Armor. They are armed with a Missile Launcher.

American T51-B Unit
This troop type wears a Winterized T-51b Power Armor and is armed with an R91 Assault Rifle.

They appear only in the U.S. Army Field Headquarters.

Power Armored Soldier
This troop type wears Winterized T-51b Power Armor. Power Armored Soldiers are armed with AER9 Laser Rifles, 10mm SMGs, R91 Assault Rifles, Chinese Assault Rifles, Super Sledges, Scoped Gauss Rifles, Miniguns, Flamers, and Fat Mans.

Most of these appear in the final confrontation with General Jingwei.

U.S. Paratrooper
Only one U.S. Paratrooper appears in the simulation, dropping from the ceiling of the Cave Outpost in The Guns of Anchorage and leaving his Scoped Gauss Rifle for you to take after his Winterized Combat Armor fails to protect him from Chinese Soldiers. There is also evidence to support that your character in the simulation is a Paratrooper as there are parachutes near where you begin.

Additional battlefield support
It seems that General Chase had access to prototype VB-02 Vertibird Gunship Support during the campaign, although this might have been one of his additions to the simulation.