Of all the special operations forces within the US military, none are as famous as the Navy SEALs. Responsible for such historic actions as the killing of Osama bin Laden, the SEALs are one of the US's go-to choices for extremely dangerous missions.
A PBS documentary, "Navy SEALs - Their Untold Story," digs into the history of the elite group's predecessors during World War II, its first official operations in the Vietnam War, and its deployment in 21st century conflicts.
Along the way, former commandos tell the stories of some of the SEALs' most incredible covert operations.
An earlier version of this post was written by Pierre Bienaimé.
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There are only around 2,000 active Navy SEALs — and they endure maybe the hardest military training anywhere in the world.
A retired SEAL explains that during the rigorous training known as "hell week,""you stay up for 120 hours ... and you get about 3 or 4 hours sleep."
Here trainees swim with their hands bound behind their backs, a feat only excellent swimmers can pull off.
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