A federal judge instructed the Trump administration on Thursday to explain why its failure to turn around flights carrying deportees to El Salvadordid not violate his court order in a growing showdown between the judicial and executive branches, Associated Press reported.

U.S. District Judge Jeb Boasberg demanded answers after flights carrying Venezuelan immigrants alleged by the Trump administration to be gang members landed in El Salvador after the judge temporarily blocked deportations under an 18th century wartime law. Boasberg had directed the administration to return to the U.S. planes that were already in the air when he ordered the halt.

Boasberg had given the administration until noon Thursday to either provide more details about the flights or make a claim that it must be withheld because it would harm “state secrets.” The administration resisted the judge’s request, calling it an “unnecessary judicial fishing” expedition, according to the Associated Press.