Here's what we know about Delta Force, the super secretive troops who went after ISIS leader Abu Bakr al-Baghdadi

Delta Force was famously involved in the 1993 operation to capture Somali militia leader Mohamed Farrah Aidid in Mogadishu and the subsequent effort to rescue Army pilot Michael Durant after his helicopter crashed during the mission.

Five Delta operators were killed in that incident, as well as 14 other US troops. Several hundred Somali fighters and civilians were also killed.

Delta was also involved in a failed effort to retrieve hostages from the US Embassy in Iran in 1980.

Delta Force has been heavily involved in the war in Afghanistan and both Iraq wars and was instrumental in capturing Saddam Hussein.

Delta pulled out of Iraq when US forces there left in 2011, but it has been a consistent presence in the fight against ISIS in the country, Wesley Morgan wrote in The Washington Post in 2015.

Delta Force had close ties with the Iraqi Kurds who were fighting ISIS and operated in Syria, including killing high-ranking ISIS leader Abu Sayyaf there in 2015, Morgan wrote.

Source: Insider

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."