SEATTLE - The U.S. Justice Department sent another round of letters to the so-called sanctuary cities of Seattle and Oakland and the state of Vermont demanding further proof that they are co-operating with immigration authorities.

The letters sent Thursday warn that the department could use subpoena power to force Seattle and Vermont to provide documents showing whether they are restricting information sharing. The department is seeking a legal opinion from Oakland on whether policies in its police manual violate the federal statute requiring information-sharing with federal immigration authorities.

"When cities and states enact policies that thwart the federal government's ability to enforce federal immigration law, they choose to place the protection of criminal aliens over the safety of their communities," Attorney General Jeff Sessions said in a statement. "The Justice Department will not tolerate this intentional effort to undermine public safety and the rule of law, and I continue to remind all jurisdictions to reconsider policies that put their residents in harm's way."

The Justice Department has threatened to deny grant money from communities that refuse to share such information.

It's part of the Trump administration's crackdown on cities and states that refuse to help enforce U.S. immigration laws. Officials have sent similar letters seeking proof of co-operation to some two dozen jurisdictions including Chicago, New York, Denver, and Los Angeles in recent months.

Seattle Mayor Jenny Durkan denounced the department's subpoena threat Friday.

"Our city complies with federal immigration law and asks that the Department of Justice and ICE do the same," Durkan said in a statement. "The federal government does not get to run our cities or convert our local law enforcement officials into immigration cops. I implore this administration to focus on real public safety threats, like the opioid crisis, instead of unnecessarily threatening our residents and mayors across the country."

Justin Berton, a spokesman for Oakland Mayor Libby Schaaf, said the city attorney is reviewing the letter.

"We just got the letter and we don't even know what it means yet," he said.

The Justice Department also on Thursday notified the District of Columbia and the Louisville-Jefferson County Metro Government in Kentucky that there is no evidence that either jurisdiction is currently out of compliance with the federal statute.

News from © The Associated Press, 2018