GUANTANAMO BAY U.S. NAVAL BASE, Cuba, (Reuters) – A simulated wave of Caribbean migrants sailed to the Guantanamo naval base this week for a training drill designed to prepare U.S. troops and security agencies who might someday have to handle the real thing. The exercise is held every two years to prepare for a potential mass migration brought on by political upheaval or natural disaster in the region. More than 500 U.S. troops and government workers flew to the Guantanamo Bay U.S. Naval Base in eastern Cuba for the drill, which started on Saturday and runs through Friday.