President Trump announces Guantanamo Bay will stay open; "new rules of engagement" for US forces in Afghanistan. #SOTU pic.twitter.com/qNc2G0uBBH

President Donald Trump announced Tuesday night during his State of the Union address that he will keep the controversial US military prison at Guantanamo Bay open, overriding former President Barack Obama’s official policy.

The White House also released an executive order from President Trump that revokes Obama’s 2009 executive order to close the detention facility, and states that the US may “transport additional detainees” to the military prison.

“In the past, we have foolishly released hundreds of dangerous terrorists, only to meet them again on the battlefield,” Trump said during his Tuesday night address. He said that he had signed an order directing the secretary of defense “to reexamine our military detention policy, and to keep open the detention facilities at Guantanamo Bay.”

The prison at US Naval Station Guantanamo Bay, colloquially known as “Gitmo,” opened on January 11, 2002, to hold prisoners captured during President George W. Bush’s war on terror in response to the 9/11 attacks.

Guantanamo became notorious for its treatment of prisoners, which included reports of abuse and the prolonged detention of suspects without formal charges. It came to be known as a symbol of US human rights abuses during the war on terror.

The news of the executive order, which is Trump's first official policy announcement about the prison, was first reported by Politico last week after it obtained a leaked State Department cable.

Karen Greenberg, director for the Center on National Security at Fordham Law School, called Trump’s new Guantanamo policy “extremely significant” in an interview on Tuesday night before the speech, and wondered if it was a symbolic return to “old practices of the war on terror that we thought we had sufficiently gotten rid of.”

The Obama administration promised to close the prison but failed

On his second day in office in 2009, President Barack Obama signed Executive Order 13492, which stated that the prison would be closed “as soon as practicable, and no later than 1 year from the date of this order.”

Obama was attempting to follow through on his campaign promise to close the infamous military prison, which has housed 780 prisoners since it opened in 2002.

He attempted to speed up the notoriously slow military commission trial process in 2009, when the five accused conspirators of the 9/11 attacks — including the accused mastermind Khalid Sheikh Mohammed — were transferred to the US to be tried in the federal court system. However, after public and political backlash, they were transferred back to the prison by then-Attorney General Eric Holder and re-charged by the military commissions.

In December 2011, Congress placed restrictions on transferring detainees to the US, for either detention or trial. The move hindered Obama’s efforts, and he ultimately failed to close the military prison before he left office.

George Clarke, a lawyer for a prisoner who has been detained for 15 years and was approved for a third-country release in 2010 but remains in Guantanamo, told me on Sunday that he has had no direct conversations with the government about potential release dates since Trump took office.

It’s still unclear whom Trump would send to the prison under his new policy

The announcement is not a total surprise. During his campaign, Trump talked about his desire to keep Guantanamo open, and even said that he would “load it up with some bad dudes” at a campaign event in February 2016. But what exactly that means in practice is yet to be determined.

The executive order released late Tuesday night uses a provision from the 2001 Authorization for Use of Military Force that says the US can detain people associated with the Taliban and al-Qaeda as well as "associated forces engaged in hostilities against the United States or its coalition partners."

The order also says that the US is currently in an armed conflict with ISIS and that "the United States may transport additional detainees to U.S. Naval Station Guantánamo Bay when lawful and necessary to protect the Nation."

This may leave the door open for Trump to begin sending people to the prison who have not traditionally been held there before, including members of ISIS.

But as for the fate of the 41 prisoners who are still in Guantanamo today, there are still no concrete answers.