The 121st Fighter Squadron (121 FS) is a unit of the District of Columbia Air National Guard 113th Wing located at Joint Base Andrews, Camp Springs, Maryland.

A Maryland Terrapin originally flew with the District of Columbia Air National Guard and, many years later, was reinstated as the unit's insignia.

"A caricatured tan and brown turtle proper , riding a "pogo" stick, leaving a trail of hops and impact marks black, all outlined light turquoise blue.

The unit was ordered to active duty in April 1941 as part of the buildup of the Army Air Corps after the Fall of France.

Transferred to the Third Air Force in September 1941, they began flying anti-submarine flights over the South Carolina coastline from airfields in the Columbia area.

Other parts of the squadron remained attached to the Ninth Air Force and Sixth United States Army Group during the Rhineland Campaign and the Western Allied invasion of Germany.

The squadron was equipped with P-47D Thunderbolts and was assigned to 113th Fighter Group, also a DC guard unit and was initially gained by Air Defense Command.

Parts were no problem and many of the maintenance personnel were World War II veterans so readiness was quite high and the planes were often much better maintained than their USAF counterparts.

After passing southbound near Gettysburg, Pennsylvania, the F-84C exploded in mid-air at tree height, left a large crater in a field, and scattered wreckage over 3 acres (1.2 hectares) of the Hilbert cornfield near the Maryland intersection of the Harney and Bollinger School roads.

Along with small parts of the aircraft, a few remains of the pilot were recovered; and the element leader in the lead F-84, 1st Lt. William L. Hall, reported "Alkire had not radioed of any difficulty before the explosion.

ADC's was experiencing difficulty under the existing wing base organizational structure in deploying its fighter squadrons to best advantage.

[8] With its return to District of Columbia control, the 121st Fighter-Interceptor Squadron was re-equipped with propeller-driven F-51H Mustangs and resumed its air defense mission of Washington, D.C.

This ADC alert lasted each and every day until the end of October 1958 Despite the reconditioning, the F-86A Sabres were weary and required a considerable amount of maintenance to keep in the air.

In January 1968, a new crisis, the seizure of the American ship USS Pueblo by North Korean forces, and again the 113th was called to active duty.

At Myrtle Beach AFB, the federalized NJ ANG 119th Tactical Fighter Squadron joined the 121st TFS on active duty.

The 113 TFW returned to Andrews AFB, in June 1969, and transitioned into the F-105D Thunderchief (AKA "Thud") in 1971, receiving Vietnam War veteran aircraft that were being withdrawn from combat.

In the air defense role these models lacked any BVR capability, limiting them only to close range combat with their gun and Sidewinder missiles.

In May 1996, the 121st Fighter Squadron deployed personnel and aircraft to Al Jaber Air Base, Kuwait to support Operation Southern Watch (OSW).

In February 1997 the 121st Expeditionary Fighter Squadron (121st EFS) was first formed from 113th personnel and aircraft and deployed to Incirlik Air Base, Turkey in support of Operation Northern Watch (ONW).

Operation Northern Watch was a US European Command Combined Task Force (CTF) who was responsible for enforcing the United Nations mandated no-fly zone above the 36th parallel north in Iraq.

The 121st EFS was again formed in January 1998 when the Wing was tasked with a second Operation Northern Watch deployment to Incirlik Air Base.

On 11 September 2001, the wing was given authorization to shoot down threatening aircraft over Washington, D.C.[9] After the events of 11 September 2001 the squadron took on an Air Sovereignty Alert Detachment role, stationing a number of aircraft at air force bases around the country to fly alert missions as part of Operation Noble Eagle (ONE).

One senior Bush administration counter-terrorism official said it was 'a real finger-biting period' because they came very close to ordering a shot against a general aircraft.

A deployment to Bagram Air Base, Afghanistan in support of Operation Enduring Freedom (OEF) was made between October 2011 and January 2012.