Guantanamo Bay, a U.S. base in Cuba since 1898, may soon house thousands of detained migrants, following a proposal by the Trump administration.

It's not clear how many beds Guantanamo has, or how Mr. Trump arrived at that number. The president has previously floated the idea of sending migrants with criminal backgrounds to be detained or imprisoned outside the U.S., although the logistics and legalities of such a feat remain unclear.