Trump made the surprise declaration during the signing of the Laken Riley Act at the White House Wednesday afternoon to prepare a migrant facility at the Guantanamo Bay detention camp, which was used to detain suspected terrorists during the George W. Bush administration.

“Today, I’m also signing an executive order to instruct the Departments of Defense and Homeland Security to begin preparing the 30,000-person migrant facility at Guantanamo Bay. Most people don’t even know about it,” Trump said.

“We have 30,000 beds in Guantanamo to detain the worst criminal illegal aliens threatening the American people,” Trump said. “Some of them are so bad, we don’t even trust [their home] countries to hold them because we don’t want them coming back. So we’re going to send them out to Guantanamo.”

The executive action, Trump said, would bring the United States “one step closer to eradicating the scourge of migrant crime in our communities, once and for all.”

The move is expected to be met with pushback from immigrant rights groups and Democratic lawmakers.

While initially popular, public outcry against Guantanamo grew throughout the Bush administration, and his successor, President Barack Obama, pledged in 2009 to close the facility within one year. However, opposition from Congress prevented Guantanamo’s closure.

Now, Guantanamo could regain a place in American foreign policy and its public consciousness. Its inmate population dwindled to just 15 people in recent years and now could swell by tens of thousands.

Trump earlier this week won a showdown against the government of Colombia, which had tried to refuse to take back migrants who legally reside in that country. Using Guantanamo can give the president a new option to house migrants from countries that refuse repatriation.

Several details of Trump’s plan remain unknown, such as the criteria for selecting detainees, how long they will be held, and under what conditions. Nonetheless, Trump says using Guantanamo is necessary as he cracks down on illegal immigration.

“Today’s signings bring us one step closer to eradicating the scourge of migrant crime in our communities once and for all,” Trump said. “It’s just an unforced error that we even have to be doing this.”

Trump’s border czar Tom Homan told White House reporters that Immigration and Customs Enforcement would be running the migrant detention.

“What you probably don’t know, there’s already a migrant center there, it’s been there for decades. So we’re just going to expand upon that existing migrant center,” Homan said alongside Homeland Security Secretary Kristi Noem.

He added that ICE has the “highest detention standards in the industry” and, therefore, “Gitmo will have the highest standards.”