U.S. President Donald Trump said on Monday he would call a national emergency and federalize Washington, D.C. after Mayor Muriel Bowser said its police would not cooperate with Immigration and Customs Enforcement.

At issue is the provision of information on individuals living in, or entering, the United States illegally. Trump’s threat adds to a move critics have seen as federal overreach, with more than 2,000 troops patrolling the city.