The Department of Justice officially kicked-off President Trump’s crackdown on ‘Sanctuary Cities’ on Friday, sending official warnings to nine municipalities that refuse to cooperate with the administration’s new federal guidelines, reports the Wall Street Journal.

The letters demand proof that the jurisdictions are complying with the newly issued rules regarding illegal aliens and immigrants, and warns them that they will lose federal funds if they continue to harbor illegal aliens and undocumented individuals. They have until the end of June to comply. 

The notices, written by Acting Assistant Attorney General Alan Hanson, were sent to the state of California, Chicago, New Orleans, Las Vegas, Philadelphia, Miami, New York, Cook County, and Milwaukee. Each municipality has laws on the books that prohibit police from transferring custody of illegal aliens over to federal immigration agencies.

Attorney General Sessions has lashed out at jurisdictions that refuse to cooperate with the Trump Administration, saying they actively undermine the DOJ’s fight against gangs, drugs, and terrorism.

"Harboring criminal aliens only helps violent gangs like MS-13,'' Sessions said this week. "Sanctuary cities are aiding these cartels to refill their ranks and putting innocent life — including the lives of countless law-abiding immigrants — in danger.''