Pentagon chief Mattis visits Guantanamo Bay

Defense Secretary Jim Mattis visited the US naval base at Guantanamo Bay on Thursday, the Pentagon said, marking his first such visit there.

"Secretary Mattis is currently visiting with troops at Guantanamo Bay for the holidays to thank them for their service," Pentagon spokesman Major Ben Sakrisson said.

Mattis was not visiting the notorious detention center itself, which still houses inmates who were captured after the September 11, 2001 attacks in America and have been held at Guantanamo ever since.

At the height of its operations after 9/11, the prison held 780 people detained mostly for their alleged ties to Al-Qaeda and the Taliban.

Since then hundreds have been transferred back to their home countries or other places.

Some of the most notorious inmates, including several alleged 9/11 co-conspirators, including accused mastermind Khalid Sheikh Mohammed, are still awaiting trial.

Of the 41 inmates remaining at Guantanamo, about 26 are trapped in legal purgatory.

These so-called "forever prisoners" have never been charged -- yet they have been deemed too dangerous to release.

Barack Obama tried throughout his presidency to shutter the jail but was rebuffed by Republican opponents.

As a candidate, Donald Trump said he wanted to fill it with "bad dudes."

Last month, Trump suggested that the man accused of conducting a deadly truck attack in New York could be sent to Guantanamo, but he later backed off the idea.

Attorney General Jeff Sessions visited Guantanamo in July.