What to know about Guantanamo Bay, the base where Trump says he’ll send migrants

President Donald Trump, who made the deportation of migrants a central part of his campaign and presidency, said Wednesday that the U.S. will use a detention center at Guantanamo Bay, Cuba, to hold tens of thousands of people who can’t be sent back to their home countries.

“We’re going to send them out to Guantanamo,” Trump said at at the signing of the Laken Riley Act.

Here’s a look at the U.S. naval base and its history:

While the U.S. naval base in Cuba is best-known for the suspects brought in after the Sept. 11, 2001, attacks, it also has a separate facility used for decades to hold migrants.

The Migrant Operations Center holds those detained at sea, many from Haiti and Cuba.

The nonprofit International Refugee Assistance Project said in a report last year that the migrants are held in “prison-like” conditions. It said migrants there were “trapped in a punitive system” indefinitely, with no accountability for the officials running it.

The U.S. has leased Guantanamo from Cuba for more than a century. Cuba opposes the lease and typically rejects the nominal U.S. rent payments.

Trump has vowed to deport millions of people living illegally in the U.S., but the current Immigration and Customs Enforcement budget only has enough funds to detain about 41,000 people.

ICE detains migrants at its processing centers and privately operated detention facilities, along with local prisons and jails. It has no facilities geared toward detention of families, who account for roughly one-third of arrivals on the southern U.S. border.

During Trump’s first term, he authorized the use of military bases to detain migrant children. In 2014, then-President Barack Obama temporarily relied on military bases to detain immigrant children while ramping up privately operated family detention centers to hold many of the tens of thousands of Central American families caught illegally crossing the border.

U.S. military bases have been used repeatedly since the 1970s to accommodate the resettlement of waves of immigrants fleeing Vietnam, Cuba, Haiti, Kosovo and Afghanistan.