The report undercuts months of assertions by senior Trump officials, who have repeatedly claimed they have no power to compel the return of these individuals.

Over 200 migrants who were sent to El Salvador's CECOT mega-prison under accusations that they were members of a violent criminal gang are the responsibility of the United States, the government of El Salvador told a United Nations working group.

The Trump admin has argued that the men are now outside U.S. legal jurisdiction and no longer protected by constitutional rights.