Delta Force: The secretive special ops unit who took out Baghdadi

THE special forces unit which hunted down ISIS leader Abu Bakr al-Baghdadi is so secretive even the Pentagon doesn't admit it exists.

Delta Force - set up by a US commander who served with the SAS - only recruits the best of the best and plays by its own combat rules.

In military circles it is known simply as 'The Unit' and is tasked with handling the most dangerous and specialised missions in the world.

However, despite its latest headline-grabbing success, very little is known about the workings of the secretive special operations division.

Delta Force has regularly been used in covert combat missions around the globe, including in Afghanistan, Iraq, Syria, Somalia and Libya.

Along with the US Navy’s Seal Team 6, Delta Force it has been working to locate and eliminate the very top members of ISIS's hierarchy.

Until now, Delta has had a lower profile than Team 6 whose exploits became world news when they shot dead Osama bin Laden in 2011.

In fact, the Pentagon does not normally even acknowledge the existence of Delta Force - something which clearly suits both parties.

Founded by Colonel Charlie Beckwith, The 1st Special Forces Operational Detachment-Delta follows the same tough selection tests as the SAS.

The spearhead unit is part of  the US Joint Special Operations Command, which works out of highly-secure Fort Bragg in North Carolina.

Delta deals with hostage rescue and counter-terrorism, as well as direct action and special reconnaissance work regarding “high-value targets”.

It's recognised as being among the most advanced units in the world when it comes to training, hi-tech equipment and armoury.

The troops even have their own team of specialist gunsmiths which develop state-of-the-art weapons just for their personalised needs.

Selection is considered the most challenging in the US armed forces - as those looking to join must already be members of other elite units.

Therefore, it is impossible to become a part of 'The Unit' immediately after enlisting.

Soldiers are carefully selected from a narrow pool after having proved themselves in battle, sometimes for  many years.

However, despite all the training, not every Delta Force mission has been a success.

The US Army unit led an attempt to rescue American and other foreign hostages held by Isis in Syria in 2014.

The hostages included James Foley, an American journalist, and Kayla Mueller, a US aid worker.

The mission failed and both American hostages and others were subsequently killed by their ISIS captors

Delta Force was also involved in a dramatic abduction in Tripoli, Libya, in 2014 when commandos seized Abu Ahmed Khattala.

He was suspected of being one of the terrorists who launched an attack on the US consulate in Benghazi on September 11 2012.

The US ambassador and three other American nationals were killed.

One of the unit’s most successful missions was against the terrorist leader who was eventually to be succeeded by Baghdadi.

In April 2006, Abu Musab al-Zarqawi, leader of al-Qaeda in Iraq, was killed in an operation involving a US airstrike and Delta Force commandos.

Baghdadi, who had joined al-Qaeda, took over and then transformed it into the Islamic State of Iraq and the Levant, the forerunner of ISIS.