Delta Force, also called The Unit or Task Force Green, is a counter-terrorism Special Missions Unit under Joint Special Operations Command, or JSOC.

The military doesn't officially acknowledge Delta Force, but its existence is well known. Many of its operations are classified and will likely never be known to the public.

In addition to physical qualifications, Delta Force operators must be psychologically fit to conduct grueling operations.

After recruits pass the physical and psychological portions of the assessment, they are taught skills like marksmanship and covert trade craft — CIA tactics like dead drops and other espionage methods — during a six-month Operator Training Course, former operator Eric Haney says in his book, "Inside Delta Force."