Attorney General Jeff Sessions on Friday demanded that nine jurisdictions produce proof that they are communicating with federal authorities about undocumented immigrants or risk losing grant funding.

Sessions sent letters to the nine jurisdictions, including Philadelphia, New York and Chicago, in the latest sign that the Trump administration intends to punish so-called “sanctuary cities” that do not cooperate in its promised crackdown on illegal immigration.

President Donald Trump signed an executive order in January declaring that sanctuary jurisdictions would not be eligible to receive federal grants, and Sessions vowed last month during a White House news conference to take Justice Department money from such places.

How far Trump can go, though, and what jurisdictions can do to avoid his ire, remains unclear.

In a news release, the Justice Department said the places were identified in a May 2016 Justice Department Inspector General’s Office report as potentially having policies that hindered communication with Immigration and Customs Enforcement.

The letters were addressed to officials in New Orleans; Philadelphia; Chicago; New York City’ Clark County, Las Vegas; Miami Dade County; Milwaukee County; Cook County, Ill. and the state of California.

The Justice Department wrote in a press release, “Additionally, many of these jurisdictions are also crumbling under the weight of illegal immigration and violent crime,” casting aspersions on New York, Chicago and the Bay Area in particular.

The release said New York, for example, which has seen significant recent reductions in crime, “continues to see gang murder after gang murder, the predictable consequence of the city’s ‘soft on crime’ stance.” It said crime in Chicago had “skyrocketed.” And it said after a raid on MS-13 members in the Bay Area, “city officials seemed more concerned with reassuring illegal immigrants that the raid was unrelated to immigration than with warning other MS-13 members that they were next.”

Several jurisdictions said they believed they already had been complying with federal law all along, and they disputed Sessions’ characterization of what was happening.

Zach Butterworth, the director of federal relations for the city of New Orleans and executive counsel to the mayor, said the city welcomed the letter and would respond next week telling Sessions they were fully complying with federal law. He said sanctuary city was an ill-defined term and New Orleans did not accept the moniker.

“There’s a lot of political talk, but there’s no legal analysis,” Butterworth said. “We say we’re not one because we follow federal law.”

While the city tells its police officers not to ask people they encounter about their immigration status, it does not block them from talking to Immigration and Customs Enforcement agents, Butterworth said. He said the city updated its policy to better reflect federal law last year.

“If they need one more letter, we’re happy to send it, and we’ll get it turned around quickly,” Butterworth said.

Mike Hernandez, the communications director for Miami Dade County, said Mayor Carlos Giménez “strongly believes that we are in compliance” with the law, and noted the county had begun earlier this year to honor all requests from Immigration and Customs Enforcement to detain potential illegal immigrants taken into custody on local charges.

Hernandez said the county had stopped honoring the requests in 2013 because the federal government was not providing reimbursement for the cost of detaining suspected illegal immigrants, but, fearing the loss of federal funding, officials had decided to change course.

“We never proclaimed to be a sanctuary community before then, and we haven’t since,” Hernandez said. “We always have worked with federal authorities on all matters, including immigration.”

Seth Stein, a spokesman for City Hall in New York, said, the administration’s push was “nothing new” and the “grandstanding shows how out of touch the Trump administration is with reality.”

“Contrary to their alternative facts, New York is the safest big city in the country, with crime at record lows in large part because we have policies in place to encourage cooperation between NYPD and immigrant communities,” he said.

Milwaukee County Executive Chris Abele said in a statement officials were “in compliance with the law and will share the required legal opinion by the date requested,” though the Justice Department’s comments about illegal immigration and violent crime were “neither accurate nor productive.”

“Milwaukee County has its challenges but they are not caused by illegal immigration,” said Abele. “My far greater concern is the proactive dissemination of misinformation, fear, and intolerance.”

That law that Sessions wants enforced is very narrow, and it would not bar any of the policies that people generally associate with sanctuary jurisdictions.

When someone is arrested on a local crime, their fingerprints are run through the FBI database, and – whether local authorities like it or not – Immigration and Customs Enforcement can tell if they are in the country illegally. Immigration and Customs Enforcement will often then send a request to local authorities to detain such people.

Refusing to honor such a request would not necessarily violate federal law. But telling local police officers, for example, that they could not give information to their counterparts in Immigration and Customs Enforcement might.

The Obama administration also had considered compliance with the law a requirement for receiving Justice Department grants, and in response to the Inspector General’s report, even issued guidance on the subject. Cities, though, have said they are worried that Sessions’ threats are not mere talk.

Seattle, San Francisco and Santa Clara County have actually sued over the matter, asking a federal judge to block Trump’s executive order and stop Sessions from making good on his threat. The Justice Department has fought the cases in court, and Acting Assistant Attorney General Chad Readler argued at a recent hearing that it was premature for the judge to consider because the Justice Department had not yet taken any sort of “enforcement action.”