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's objective is to send groups of unauthorized migrants from the U.S. mainland to Guantanamo each day, using military aircraft to airlift and relocate detainees.

About 300 servicemembers have arrived in recent days as the base faces its most drastic changes since the Pentagon opened a prison there after the Sept. 11 attacks.