They are a mixture of Green Berets, Rangers and the Delta Force from the Army, the Seals (which stands for Sea-Air-Land) from the Navy and the Air Force's combat controllers and para rescue teams.

BBC: Snipers

He worried the troops would reject him because he had not served in any of its elite units such as the Army's Delta Force or the Navy's SEAL Team 6.

NPR: McChrystal Takes Blame For Rolling Stone Article

It will be up to the military service chiefs to recommend whether women should be excluded from more demanding and deadly positions, such as Navy SEALs or the Army's Delta Force.

WSJ: Women in combat face doubts over emotions, ability