The Trump administration on Tuesday began flying immigrants who entered the country illegally to Guantánamo Bay amid plans to use the facility in Cuba to detain thousands of migrants.

White House press secretary Karoline Leavitt confirmed the first flights from the U.S. to Guantánamo Bay carrying migrant lacking permanent legal status were underway.

“President Trump is not messing around, and he’s no longer going to allow America to be a dumping ground for illegal criminals from nations all over this world,” Leavitt said on Fox Business Network.

Trump last week signed a memo directing the Department of Defense and Department of Homeland Security to prepare a 30,000-person migrant at Guantánamo Bay, a facility in Cuba that has been used to house military prisoners, including several involved in the 9/11 attacks.

Guantánamo Bay is best known as a military base where terror suspects are held. It became infamous for accusations of torture and abuse as the U.S. carried out the war on terrorism. The Biden administration sought to wind down operations at the facility. There are 15 detainees still there.

“Due process will be followed, and having facilities at Guantánamo Bay will be an asset to us,” Homeland Security Secretary Kristi Noem said Sunday on “Meet the Press.”

Noem would not say whether women and children would be kept at Guantánamo Bay.

The Trump administration has aggressively moved to remove individuals who entered the U.S. illegally, setting up agreements with Colombia, Venezuela and El Salvador for those countries to accept deported immigrants.