The Trump administration sued Chicago on Thursday alleging that 'sanctuary' laws in the nation's third-largest city “thwart" federal efforts to enforce immigration laws.

The lawsuit, which also names the state of Illinois, is the latest effort to crack down on places that limit cooperation between federal immigration agents and local police. It follows the federal government's threats of criminal charges and funding cuts to what are known as sanctuary cities.

“The conduct of officials in Chicago and Illinois minimally enforcing — and oftentimes affirmatively thwarting — federal immigration laws over a period of years has resulted in countless criminals being released into Chicago who should have been held for immigration removal from the United States," according to the lawsuit filed in Chicago's federal court.

President Donald Trump has often singled out Chicago and Illinois because they have some of the nation's strongest protections for immigrants. Top administration officials last month visited the city to launch stepped up immigration enforcement and showcased footage of “border czar” Tom Homan making arrests.

The aggressive approach and harsh rhetoric have been heavily criticized by the political left for stoking fears in immigrant communities and feeding claims about crime among immigrants.

Several high-profile and violent crimes involving people in the U.S. illegally have been in the news in recent months. The sentiment is the cornerstone of Trump's agenda. The first bill he signed of his new administration, named after slain Georgia nursing student Laken Riley, requires the detention of immigrants in the country illegally who are accused of theft and violent crimes.

Hours after new Attorney General Pam Bondi was sworn in Wednesday, she ordered an end to Department of Justice grants for jurisdictions that “unlawfully interfere with federal law enforcement.”

Courts, however, have repeatedly upheld the legality of the range of sanctuary laws, so it's not clear how this may play out. The laws do not allow local law enforcement to actively interfere with federal operations. The first Trump White House also tried to deny public safety grants to sanctuary jurisdictions, but courts largely rejected those attempts.

California Democrat Attorney General Rob Bonta said he is monitoring the directive's implementation.

“We won’t hesitate to respond if the Trump administration attempts to delay or unlawfully condition vital public safety funding for state and local law enforcement,” he said in a statement.

Immigration advocates expect the administration to use a range of political tools against sanctuary jurisdictions, from legislation to Bondi’s directives to threats to restrict funding from agencies including the Department of Transportation.

“This is going to be an ongoing attack on all fronts and in multiple agencies,” Kerri Talbot, the co-executive director of the Immigration Hub, a pro-immigration policy group, told reporters.

The lawsuit against Chicago claims that local laws run counter to federal laws by restricting “local governments from sharing immigration information with federal law enforcement officials” and preventing immigration agents from identifying “individuals who may be subject to removal.”

Heavily Democratic Chicago has been a sanctuary city for decades and has beefed up its laws several times, including during Trump’s first term in 2017. That same year, then-Gov. Bruce Rauner, a Republican, signed more statewide sanctuary protections in law, putting him at odds with his party.

Chicago Mayor Brandon Johnson said Chicago will remain a welcoming city. He and other mayors plan to testify next month at a congressional hearing on sanctuary cities. In recent months, Chicago has helped host trainings for people to learn their rights when it comes to immigration agents and publicized the information at public transit stations.

“The safety and security of Chicago residents remains the priority,” he said in a statement Thursday. “Chicago will continue to protect the working people of our city and defend against attacks on our longstanding values.”

Illinois Democratic Gov. JB Pritzker said the state has always complied with the law.