The mission of the 159 FS is to provide air defense for the southeastern United States, as directed by the North American Aerospace Defense Command (NORAD) and United States Northern Command (USNORTHCOM), in an area stretching from offshore of Charleston, South Carolina to the southern tip of Florida and across the Florida panhandle.

[1] The squadron, as part of its parent wing, is also available to other combat commanders for forward deployment in order to perform air superiority/air dominance missions in other theaters outside of the United States.

It attacked such targets as German and German-occupied airdromes, marshalling yards, missile sites, industrial areas, ordnance depots, oil refineries, trains and highways.

It then deployed to Chievres Airdrome (ALG A-84), Belgium between February and April 1945 flying tactical ground support missions during the airborne assault across the Rhine.

At the conclusion of World War II, work began to organize an Air National Guard unit for Florida.

A National Guard Bureau document dated 16 March 1946, gave states permission to request an Army Air Forces unit allotment.

Governor Millard F. Caldwell formally accepted the unit on 30 August 1946, and full federal recognition was granted 9 February 1947.

A facility for housing the units became available in temporary World War II buildings on the west side of the Thomas Cole Imeson Airport in Jacksonville, Florida.

The conversion from the F-51D Mustang to the F-80C Shooting Star became official on 1 August 1948, when the unit was re-designated the 159th Fighter Squadron, Jet Propelled (159 FSJ).

The group received instructions to move to the Far East, which overrode their original orders to Europe to replace an active duty U.S. Air Force squadron slated to go to Korea.

There, the 159 FSJ concentrated on flying dangerous ground attack missions against enemy supply lines and troops in the field.

By 1 July 1956, the parent unit reorganized into 125th Fighter-Interceptor Group (125 FIG) and both organizations were operationally gained by Air Defense Command (ADC).

The F-86 made the 125th a self-sustaining unit capable of performing the Air Defense mission in all types of weather, day or night.

Due to its limited ability to handle newer commercial jet aircraft, the local government officials in Jacksonville and Duval County in the early 1960s determined that Imeson Airport would need to be replaced by a newer, larger airport with a greater capability for accommodating jet airliner traffic and long-term growth.

By the end of the year, with the conversion complete and the F-106 formally integrated into the 125 FIG weapons inventory, alert status resumed at Jacksonville International Airport.

Pilots and ground crew members received extensive training in the operations and maintenance of the F-106 and they soon gained the expertise needed to handle the sophisticated all-weather supersonic fighter-interceptor.

The 125 FIG was concurrently redesignated as the 125th Fighter Group (125 FG) and both organizations operationally gained by the newly established Air Combat Command (ACC).