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 first U.S. military aircraft carrying detained migrants to Guantanamo Bay is expected to depart on Tuesday, U.S. officials said, as President Donald Trump's administration prepares to potentially house tens of thousands of migrants at the naval base in Cuba.