The 1st Special Forces Operational Detachment-Delta (SFOD-D), commonly referred to as Delta Force, Combat Applications Group (CAG), "The Unit", Army Compartmented Element (ACE), or within JSOC as Task Force Green, is an elite special mission unit of the United States Army, under operational control of the Joint Special Operations Command. The unit is tasked with specialized missions primarily involving hostage rescue and counter-terrorism, as well as direct action and special reconnaissance against high-value targets. Delta Force and its maritime counterpart, the U.S. Navy's SEAL Team Six (also known as the Naval Special Warfare Development Group or DEVGRU) are the U.S. military's primary counterterrorism units. Delta Force and DEVGRU perform the most complex, classified, and dangerous missions in the U.S. military, as directed by the U.S. National Command Authority.
Most Delta Force operators are selected from the United States Army Special Operations Command's elite Special Forces Groups and the 75th Ranger Regiment, as well as from other special operations units.