The United States has started sending more migrants deemed by officials to be “high threat” criminal aliens to the U.S. naval base at Guantanamo Bay, Cuba, just days after emptying out the base’s migrant facilities.

The base had been cleared of migrants since Thursday, after the government sent 177 to Venezuela and one back to the United States.

CARACAS, Venezuela (AP) — Nearly 200 Venezuelan immigrants to the U.S. were returned to their home country after being detained at Guantanamo Bay, in a flurry of flights that forged an unprecedented pathway for U.S. deportations.

A group of five Senate Democrats led by Sen. Dick Durbin (D-Ill.) sent a letter to President Trump Monday challenging his transfer of migrants to detention centers at the U.S. Naval station in

President Donald Trump’s border czar, Tom Homan, confirmed that the administration will continue to use Guantanamo Bay as a holding facility for migrants after the Department of Homeland Security transferred over a hundred Venezuelan detainees out of the facility on Thursday.

The Trump administration has said little about the Venezuelan men who were transferred from Texas to the U.S. military base in Cuba.

The number of troops being sent to Guantanamo Bay, Cuba, in support of migrant detention operations there continues to swell, with approximately 1,100 service members now deployed to the Navy base.

The administration flew almost all of the migrants it had held in the facility in Cuba to Honduras, and one to detention in the U.S., NBC News has learned.