The U.S. Justice Department sued the state of Illinois and city of Chicago on Thursday, accusing the Democratic strongholds of unlawfully interfering with Republican President Donald Trump's crackdown on illegal immigration and seeking a court order blocking so-called sanctuary laws.

The Trump administration is suing Chicago over what are known as sanctuary laws. The administration claims the nation’s third-largest city “thwarts” federal efforts to enforce immigration laws.

It appears to be the first Justice Department lawsuit against local officials for allegedly interfering with the Trump administration’s immigration crackdown.