President Donald Trump’s use of the Guantanamo Bay naval base to house migrants appears to cost $100,000 per day for each detainee, U.S. Senator Gary Peters said during a hearing on Tuesday, decrying what he described as a prime example of wasteful government spending.

Peters, the top Democrat on the Senate Homeland Security and Governmental Affairs Committee, questioned Homeland Security Secretary Kristi Noem about the high cost, far more than the $165 per day in U.S. immigration detention facilities. Peters also asked why detainees have been sent to the American naval base in Cuba but then shuttled back to the United States at taxpayer expense.

A U.S. official, speaking on condition of anonymity, said there were roughly 70 migrants currently detained there.