Five senators who visited the U.S. base at Guantánamo Bay, Cuba, criticized the migrant mission there over the weekend as a waste of resources, after the Pentagon estimated that the operation had cost $40 million in its first month.
The Senate delegation on Friday toured Immigration and Customs Enforcement facilities where about 85 migrants were being held, including in a prison that for years housed wartime detainees linked to Al Qaeda.
The senators also spoke with officials from the Defense and Homeland Security Departments. About 1,000 government employees, mostly from the military, are staffing the migrant operation.
The administration has sent fewer than 400 men, at least half of them Venezuelans, to the base since February as part of President Trump’s crackdown on illegal immigration. The authorities returned about half of them to facilities in the United States without explaining why scores of people needed to be housed at Guantánamo for short stays.
As of Sunday, there were 105 immigration detainees at the base.
Senator Jack Reed of New Hampshire, who was part of the delegation, faulted the administration on Sunday for “diverting troops from their primary missions” to Guantánamo.
Mr. Reed, the ranking Democrat on the Armed Services Committee, said in an interview that he was provided with an estimate that the operation had cost $40 million in the first month.