In conventional settings, TACPs are the principal Air Force liaison element to the United States Army (USA). In this context, the TACP is an Air Force liaison element aligned with Army combat maneuver echelons from Corps to Battalion level. The TACP provides its aligned Army unit with expertise in planning and executing airpower in support of the land component commander's scheme of maneuver. In special operational settings, TACPs deploy with special operations units, including Air Force Special Tactics, Army Special Forces, and Navy SEAL teams, the 75th Ranger Regiment, and Joint Special Operations Command Special Mission Units, acting primarily as precision airstrike controllers and communication/C2 experts.
Being a conventional TACP is already a challenging and arduous task, but couple that intensity with the demanding and specialized operations of the U.S. Army Rangers, Special Forces, and U.S. Navy SEALs and you'd be describing the mission of an Special Tactics TACP. Special Tactics TACP Airmen deploy with Special Operations Forces to provide Joint Terminal Attack Control, or JTAC. Integrating air combat power and surface fires into the ground scheme of maneuver, they enable dynamic, synergistic, and lethal firepower on today's battlefield. Special Tactics TACP motto: "100%, and then some". ST TACPs are assigned to the 17th Special Tactics Squadron at Ft. Benning, Ga., Joint Base Lewis McChord, Tacoma, Wa., Hunter Army Airfield, Savannah, Ga., and all four active duty Special Tactics Squadrons located in the continental United States.
The US Special Operations Command was established in 1987 at MacDill AFB, FL. One MSgt. 1C4X1 (then AFSC 275X0) was assigned to the command as a liaison, but the position was disestablished in approximately 1991. In 1997, two MSgt. JTAC-qualified 1C4X1s assigned to the 17th ASOS at Ft. Benning, GA were selected for assignment to two of the Air Force Special Operations Command's Special Tactics Squadrons. Since then, the 17th ASOS, which provides JTACs and ALOs to the 75th Ranger Regiment and its three line battalions, has transferred from Air Combat Command to Air Force Special Operations Command and in July 2013 was renamed 17th Special Tactics Squadron. JTAC-qualified 1C4X1s at the "5" or "Craftsman" skill level may apply for a Special Tactics assignment within Air Force Special Operations Command (AFSOC). After a rigorous selection process and training program, AFSOC 1C4X1 JTACs provide terminal attack control and fire support expertise for the three Ranger Battalions, the 75th Ranger Regiment's Reconnaissance Company, all seven Army Special Forces Groups, multiple Naval Special Warfare Groups (SEAL Teams), and all four active duty CONUS Special Tactics Squadrons.
The above information provided in part by Wikipedia, The Institute of Heraldry, Global Security, and the official websites of the corresponding units and formations.