The first U.S. military flight deporting migrants from the United States to Guantanamo Bay has landed in Cuba.

The Pentagon has said it plans to deport more than 5,000 migrants held by U.S. authorities in El Paso, Texas, and San Diego, California.

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,