A U.S. federal judge asked the Trump administration to explain how it failed to act on its court order to halt the deportation of hundreds of Venezuelan migrants, including alleged gang members, escalating the confrontation between the President and the federal judiciary.

More than half of the 261 immigrants expelled to El Salvador on Saturday were swept out of the United States using a wartime powers act, a White House official said Sunday, amid questions about whether the Trump administration flouted a judge’s order barring use of the statute to hasten deportations.

The Alien Enemies Act of 1798 gives the president wartime powers to deport undocumented immigrants with little to no due process.