The proposal is almost certainly illegal, experts said, but President Trump’s eagerness to entertain it showed his willingness to embrace extreme measures to demonstrate he is tough on crime.

The Trump administration and the president of El Salvador said they struck a deal allowing the U.S. to ship detained migrants and imprisoned criminals to a mega-prison there

SAN JOSE, Costa Rica (AP) — Secretary of State Marco Rubio said Tuesday that El Salvador’s offer to accept and jail violent American criminals raises clear legal issues but described it as “very generous” and said that President Donald Trump would make a decision on whether to accept it.

A U.S. official said the Trump administration had no current plans to try to deport American citizens—but said Bukele’s offer was significant.

Secretary of State Marco Rubio said El Salvador's president will accept deportees of any nationality, including violent American criminals imprisoned in U.S.

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.

It is illegal to send US prisoners to another country and would likely be in violation of the Constitution and the protection against cruel and unusual treatment

El Salvador has offered to take in people deported from the U.S. for entering the country illegally as well as the country’s violent criminals — even if they’re American citizens

Secretary of State Marco Rubio said El Salvador agreed to take deportees and "dangerous" U.S. criminal citizens.

He met with Salvadoran President Nayib Bukele and senior officials at Bukele's residence on Lake Coatepeque outside the capital for almost three hours, where they agreed to go beyond El Salvador's acceptance of its own deported citizens.