President Donald Trump accused Minneapolis Mayor Jacob Frey of breaking the law on Wednesday after Frey stated that “Minneapolis does not and will not enforce federal immigration laws.”

“Could somebody in his inner sanctum please explain that this statement is a very serious violation of the Law, and that he is PLAYING WITH FIRE!” Trump wrote on Truth Social on Tuesday in response.

Frey made the comment in a social media post the previous day, saying he had “made it clear” to White House border czar Tom Homan, who Trump has dispatched to Minneapolis to take over his Administration’s immigration operations in the area, that local officers would not carry out federal immigration enforcement.

Trump had appeared to soften his tone toward the mayor, as well as Minnesota Gov. Tim Walz, earlier this week as the President sought to quell bipartisan backlash to his immigration crackdown following the second fatal shooting by federal agents in the city in less than three weeks.

He characterized Frey’s statement as surprising in his Tuesday post, noting that it came after what he called “a very good conversation” with the mayor—before ratcheting up the rhetoric again with his accusation.

Frey engaged further, responding to the President that “the job of our police is to keep people safe, not enforce fed immigration laws."

Courts have repeatedly ruled that the federal government cannot force states and cities to enforce its immigration laws and have rejected challenges to so-called sanctuary city policies that limit local law enforcement’s cooperation with federal enforcement operations.

In the Supreme Court’s 1997 Printz v. United States ruling, Justice Antonin Scalia wrote in the majority opinion that “it is incontestible that the Constitution established a system of ‘dual sovereignty.’ Although the States surrendered many of their powers to the new Federal Government, they retained ‘a residuary and inviolable sovereignty.’”

Scalia reiterated the court’s ruling in a prior case that “the Federal Government may not compel the States to enact or administer a federal regulatory program.” Requiring local law enforcement officers to help enforce aspects of a federal law—in the case at issue in Printz, background check requirements for firearm purchasers—“plainly runs afoul of that rule,” he wrote.