The first flight carrying migrants to Guantanamo Bay is en route and will arrive Tuesday evening, a U.S. Transportation Command official said.

As tents went up in Guantanamo Bay, Cuba to hold migrants, attorneys at the Department of Homeland Security and Pentagon were still trying to determine whether it was legal to take the unprecedented step of flying migrants from the US southern border to the facility,

The Trump administration has said it would expand operations at the American base in Cuba to hold up to 30,000 immigrants