Under U.S. immigration law, a country such as El Salvador can accept someone deported from the U.S. who isn’t a citizen of that country if the person’s homeland refuses to accept them, says Theresa Cardinal Brown, a former homeland security official under the administrations of Presidents George W. Bush and Barack Obama.

President Nayib Bukele has offered to jail deported criminals from the United States. His prisons have earned him a reputation as being tough on crime, but have raised alarms over rights abuses.

El Salvador has agreed to house violent US criminals and receive deportees of any nationality, US Secretary of State Marco Rubio announced Monday, in an unprecedented – and legally problematic deal – that has alarmed critics and rights groups.