United States Armed Forces

The United States Armed Forces were the overall unified military forces of the United States before the Great War, composed of the United States Army, United States Marine Corps, United States Navy, United States Coast Guard, and United States Air Force. The President served as the Commander-in-Chief of the military, with the Secretary of War, Department of War, and Department of Defense acting as the principal organ by which military policy was carried out.

After the Great War, descendants of the United States Armed Forces became the Enclave military forces. The Brotherhood of Steel, on the other hand, was started by former U.S. soldiers who rebelled against their unethical orders.

Before the War
By 2077, the U.S. Armed Forces were the world's most powerful military force. The only rival was the People's Liberation Army of China, with which the Armed Forces clashed during the Sino-American War, both in the Alaskan campaign (which included Anchorage) and numerous offensive campaigns waged in China.

The Armed Forces were primarily using energy weapons (laser and plasma) in the field, although due to slow production rates, many troops, in particular on the Anchorage Front Line, were still using regular firearms (such as the R91 assault rifle). Regular infantrymen, regardless of specialization, wore polymer combat armor (Anchorage troops used special winterized versions), while suits of power armor were reserved for Mechanized Cavalry units and special detachments (e.g. Colonel Spindel's group at Mariposa).

In a supportive role, the Army deployed robots―Sentry bots and combat versions of the popular Mister Handy―Mister Gutsy. Aerial support was to be provided by next-generation helicopters, the VB-02 Vertibirds, though they were scheduled to enter service in 2083, prototypes may have seen combat at Anchorage.

Fighter support was common and many patrolled the U.S. coastline and its national waters.

Army
Army units was deployed in Alaska, 2067 to fend off the Chinese military. Later in the Sino-America war, Army units were deployed in China with the USMC.

Marine Corps
The Marine Corps served as the spearhead of the American counterinvasion of China during the war, due to their specialization in amphibious operations.

Navy
The only known remaining Naval ship of the United States Navy is the Aircraft Carrier used as a settlement known as Rivet City. Located on the East Coast in Washington D.C. The U.S. Navy was also deployed during the Anchorage Reclamation, as two vessels, USS Ebon Atoll and USS Interference, are mentioned in Fallout 3.

Air Force
The United States had many Air Force bases throughout the country, some of which are, Adams Air Force Base in Virgina, and Nellis Air Force Base in the Mojave Desert.

National Guard
The National Guard were a reserve branch of the Army and primarily served as a domestic defense and disaster relief force during peacetime. However, they could be and often were deployed abroad as front-line troops in wartime.

Notable operations

 * By far, the most notable operation is the Anchorage Reclamation, an 11-year campaign to liberate Alaska from the Chinese invaders. Ultimately successful, it was the first large-scale deployment of newly developed T-51b power armor units.
 * The annexation of Canada was also performed by the United States military, whose units were also dedicated to keeping the peace―by any means necessary.
 * Veterans of the Anchorage campaign were also deployed against their fellow countrymen, to contain food riots.
 * The Gobi Campaign, where the U.S. attempted to capture Chinese military facilities in the Gobi Desert. The Gobi Campaign scout rifle was designed for this campaign.
 * The Yangtze Campaign, during which Nanjing and Shanghai were occupied by Marines equipped with new, high-tech weapons and armor.

After the War
With the nuclear holocaust of 2077 and the dissolution of the chain of command, the U.S. Armed Forces effectively ceased to exist, becoming groups of isolated soldiers with no coordination. Two groups, the Enclave and the Brotherhood of Steel are known to be direct descendants (or include descendants of) the original United States Armed Forces.

Alaska

 * Artillery Overlook
 * US Army Field Headquarters
 * Elmendorf Air Force Base

West Coast

 * Mariposa Military Base
 * Lost Hills Security Bunker
 * Sierra Army Depot
 * Toxic Waste Dump Security Bunker
 * Nellis Air Force base
 * Hidden Valley

Midwest

 * Tibbets Military Prison
 * Los Alamos
 * MacArthur Army Base
 * Bunker Alpha, Beta and Gamma (original names not known)
 * Preoria facility
 * Cheyenne Mountain
 * Kansas City silo complex

East Coast

 * Fort Bannister
 * Fort Constantine
 * Fort Independence
 * National Guard Depot
 * Turtledove Detention Camp
 * Wheaton Armory
 * Rivet City Aircraft Carrier
 * The Citadel (formerly the Pentagon)
 * Albany Terrorist Prison, New York City