President Donald Trump's decision to keep Guantanamo Bay open marks the start of a new chapter for the prison, and highlights the administration's intentions for captured Islamic State militants.
Trump signed an executive order late Tuesday reversing his predecessor Barack Obama's ultimately fruitless 2009 directive to shutter the facility that has drawn global scorn.
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Trump's order indicates the prison could be needed for Islamic State fighters, hundreds of whom have been captured by the Syrian Democratic Forces (SDF), a US-backed alliance in northern Syria.
"I am asking Congress to ensure that in the fight against ISIS and Al-Qaeda, we continue to have all necessary power to detain terrorists wherever we chase them down, wherever we find them, and in many cases for them, it will now be Guantanamo Bay," Trump said during his State of the Union Speech on Tuesday.
Under president George W. Bush, the military hastily built the prison camp in southeastern Cuba following the US-led invasion of Afghanistan in late 2001.
Roughly 780 people have been detained at Guantanamo, mostly for their alleged ties to Al-Qaeda and the Taliban. The prison predates Islamic State by years.
US military officials have recently began openly discussing the fate of IS detainees, mainly foreign fighters, held by the SDF and other US-backed militias in northern Syria.
General Paul Selva, vice chairman of the Joint Chiefs of Staff, says there are now 'hundreds' of such detainees.Officials are worried those held en masse could become even more radicalized.
It's an experience America remembers well from the Iraq war, when the US held hundreds of prisoners, including Abu Bakr al-Baghdadi, at a camp on the Kuwaiti border. He was eventually released and went on to lead Islamic State.
"In the past, we have foolishly released hundreds of dangerous terrorists, only to meet them again on the battlefield - including the ISIS leader, al-Baghdadi," Trump said.
Colonel Ryan Dillon, a spokesperson for the US-led coalition fighting Islamic State, said the SDF captures about six foreign fighters a day.
The US and the SDF are communicating with the militants' home nations in attempts to repatriate them, but some countries do not recognize the SDF and will not work with them.
"This is a global issue, a global challenge that needs to be addressed," Dillon told AFP.
As things stand, Guantanamo has not received any new inmates since 2008. Spokesperson Commander Sarah Higgins said there were currently no plans to change that.
"We are not, at this time, adding more personnel," she said. But on the campaign trail, Trump vowed to load Guantanamo with "bad dudes," and said it would be 'fine' if US terror suspects were sent there for trial.
Since becoming president, Trump has even mused about sending Americans to Guantanamo, though federal judges would likely bar any such attempt.
His order states it should not be "construed to affect existing law or authorities relating to the detention" of US citizens.
Still, Trump in October suggested the man accused of carrying out a deadly truck attack along a bike path in New York could be sent to Guantanamo, but he soon backed off the idea.
Rights groups, critics and legal observers reacted swiftly to Trump's order, blasting both the cost of the prison and the image it projects to the world.
"Guantanamo has been proven time and again to be harmful to America's values and security," American Civil Liberties Union attorney Jonathan Hafetz, who has helped litigate for Guantanamo detainees and written extensively about the prison, told AFP.
"It does not enhance America's security to hold detainees at an offshore prison established to keep individuals outside the country and deny them the right to a fair trial".
The ACLU said it costs the American taxpayer $445 million a year to detain the remaining inmates. Critics say it would be far cheaper and speed up prosecutions if the men were moved to a maximum-security prison in America.
But conservative lawmakers lauded Trump's order, pointing to figures showing some former Guantanamo detainees had taken up arms again.
"Far too many terrorists released from GTMO have returned to the fight and directly threaten the safety of American troops and our citizens at home and abroad," Republican Senator Marco Rubio said, using the military abbreviation for Guantanamo.
The top Democrat on the House Armed Services Committee, Representative Adam Smith, accused Trump of "taking us in the wrong direction".
"Today, Guantanamo continues to be an international eyesore that undercuts our national security, damages our credibility with our international partners and is a colossal waste of taxpayer dollars", he said.
First under Bush and then under Obama, the US released hundreds of detainees from the prison.
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The most notorious inmates, including several alleged 9/11 co-conspirators - among them accused mastermind Khalid Sheikh Mohammed - are still awaiting trial.
Their cases have been beset by legal woes in Guantanamo's much-maligned criminal justice system that grants detainees - who are considered "unprivileged enemy belligerents" - only some of the legal rights that US federal courts guarantee.
Of the 41 inmates remaining, 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.