Guantanamo Bay prison has been open for more than 16 years, and it's going to remain that way under the Trump administration, President Donald Trump said during his State of the Union address on Tuesday.

"Today, I am keeping another promise," said Trump as he announced his decision to keep the prison, located in Cuba, open.

"I just signed an order directing [U.S. Secretary of Defense Jim Mattis] to reexamine our military detention policy and to keep open the detention facilities in Guantanamo Bay," Trump continued.

Under the order, the U.S. maintains the option to keep additional enemy combatants at Guantanamo when lawful and necessary to protect national security. It requires Mattis to recommend criteria for determining the fate of individuals captured by the U.S. in armed conflict.

"We must be clear: Terrorists are not merely criminals. They are unlawful enemy combatants," Trump said. "In the past, we have foolishly released hundreds and hundreds of dangerous terrorists only to meet them again on the battlefield, including the ISIS leader, [Abu Bakr al-Baghdadi], who we captured, who we had, who we released."

The detention center, often referred to as "Gitmo," opened in January 2002 under former President George W. Bush as a place to detain and interrogate people with suspected links to terrorism in the wake of the 9/11 attacks.

According to the American Civil Liberties Union, 779 men have been imprisoned at the detention center since it opened. As of September 2017, 41 remain.

Trump has repeatedly voiced his support for the continued operation of the military prison.

During his presidential campaign, Trump said he wanted to load the military up with some "bad dudes."

He also criticized former President Barack Obama's plan close the detention center as well as prohibit some of interrogation techniques.

"122 vicious prisoners, released by the Obama Administration from Gitmo, have returned to the battlefield. Just another terrible decision!" Trump tweeted in March 2017.

This year, Trump said he'd "love" to send the New York City truck attack suspect to Guantanamo.

"But statistically that process takes much longer than going through the Federal system," the president said in November.

Fox News' Kaitlyn Schallhorn and The Associated Press contributed to this report.