Illinois Governor JB Pritzker said he is making every effort to stop United States President Donald Trump “from using the military to invade states”, as the Administration threatens to deploy the National Guard to Chicago.

The comments came after Chicago Mayor Brandon Johnson (Democrat) signed an executive order instructing police not to co-operate with troops or federal agents in the event of such a deployment.

Johnson, surrounded by other city leaders, signed the order that also directs police not to wear masks and to use body cameras, while also launching a programme to educate residents on how to prepare in the event they are detained by federal agents.

“We send a resounding message to the federal Government: we do not need nor want an unconstitutional and illegal military occupation of our city,” Johnson said earlier.

“We do not want military checkpoints or armoured vehicles on our streets, and we do not want to see families ripped apart.”

Trump has suggested expanding the use of troops in cities across the US to stop what he sees as rampant crime and to bolster a crackdown on undocumented immigrants, while also ordering the National Guard to prepare for deeper involvement in policing civil unrest.

The Washington Post first reported earlier this month that the Pentagon has been planning a military deployment in Chicago for weeks, in a model that could later be used for other cities.

Immigration and Customs Enforcement has requested to use a Navy base north of Chicago as its launchpad for a crackdown on undocumented immigrants.

State and local leaders have criticised the plan as unlawful and unnecessary.

“I’ve been standing up to Donald Trump, and I’m going to do everything I can to stop him from taking away people’s rights and from using the military to invade states,” Pritzker said on CBS today after Trump blasted the Democrat on Truth Social the previous day.

“JB Pritzker, the weak and pathetic Governor of Illinois, just said that he doesn’t need help in preventing CRIME. He is CRAZY!!! He better straighten it out, FAST, or we’re coming!” the President said in a post.

Chicago is among the many large cities across the US where crime has fallen in recent years. By mid-August, the city saw a 23% decline in violent crime compared with the same period last year, according to Chicago Police Department figures.

Chicago’s reaction contrasts with the more conciliatory approach of Mayor Muriel Bowser (D) in Washington DC, where the National Guard was deployed earlier this month. US Attorney Jeanine Pirro said on Fox News that there have been more than 1500 arrests related to the deployment.

Republicans have backed Trump’s move in D.C.

“Look at what the citizens are saying. They feel safer, they are pleased that there is enforcement and a presence,” said Senator Marsha Blackburn (R-Tennessee).

“President Donald Trump has been right on this from day one, and I think people are grateful to see this. Everyone wants their community safe.”

However, as a federal district, DC is subject to greater oversight by the president and Congress than a city like Chicago or Los Angeles.

Trump deployed the National Guard to LA in June amid broad protests of his Administration’s aggressive effort to arrest and deport undocumented immigrants.

The Administration has since argued that the deployment was a success and should be duplicated elsewhere.

“LA wouldn’t be standing today if President Trump hadn’t taken action, then that city would have burned down if left to the devices of the mayor and the governor of that state,” said Homeland Security Secretary Kristi Noem today.

“There’s a lot of cities that are dealing with crime and violence right now. And so, we haven’t taken anything off the table.”

Noem encouraged major cities - including San Francisco, Boston, and Chicago - to work with the federal Government to improve public safety.

Trump has also threatened to deploy troops in Baltimore, igniting a feud with Maryland Governor Wes Moore (D).

Whether criminal charges against those arrested amid deployments will stand up in court is unclear, with judges questioning the legality of federal agents’ tactics.

Grand juries in Washington and LA have also refused to indict some individuals for alleged crimes, including a man who threw a sandwich at law enforcement officers.