US President Donald Trump said Tuesday that he will deploy National Guard troops to Chicago, calling the Democratic-run midwestern city a "hellhole" ravaged by gun crime.

"We're going in," the Republican president told reporters, while hinting that he would also send soldiers to Baltimore, another Democratic-run city.

Trump denied charges he is strictly targeting cities run by his political opponents for his anti-crime campaign and his crackdown on undocumented migrants.

"I have an obligation," he said, citing Chicago crime statistics. "This isn't a political thing. I have an obligation when 20 people are killed over the last two and a half weeks and 75 are shot with bullets."

Trump, who already sent National Guard troops into the streets of Democratic-run Washington, DC, last month, declined to say exactly when he would send soldiers to Chicago, where the Democratic state governor and mayor strongly oppose the plan.

"Chicago is a hell hole right now. Baltimore is a hell hole right now," Trump said.

Posting earlier on his Truth Social platform, the Republican president said he "will solve the crime problem (in Chicago) fast, just like I did in DC."

"Chicago is the worst and most dangerous city in the World, by far," he said, adding that JB Pritzker, the Democratic governor of the state of Illinois where Chicago is located, "needs help badly, he just doesn't know it yet."

Trump followed up with a provocative, all-caps post: "CHICAGO IS THE MURDER CAPITAL OF THE WORLD!"

Pritzker has clashed with Trump in recent days, accusing the president of preparing "an invasion."

President as police chief?

Trump ordered the deployment of the National Guard into Washington in August, and repeated his claims on Tuesday that it has improved city safety.

"It's now a safe zone," he said. "We have no crime."

Thousands of National Guard troops and US Marines were deployed to Los Angeles in June to assist police as they cracked down on protests and unrest in the California city over Trump's sweeps for undocumented migrants.

On Tuesday, a federal judge declared that Trump effectively violated the law when he used troops in Democratic-run Los Angeles, and barred National Guard reservists or Marines from performing police functions including arrests or searches and seizures.

District Judge Charles Breyer in San Francisco warned in his ruling that Trump appears intent on "creating a national police force with the President as its chief."

Breyer's injunction, however, would only come into force on September 12, potentially leaving an opening for the conservative-majority Supreme Court to rule on the case.

As Chicago residents braced for a possible intervention by Trump, its Democratic mayor delivered a spirited defense of the Windy City.

"No federal troops in the city of Chicago! No militarized force in the city of Chicago!" Mayor Brandon Johnson said Monday at a rousing Labor Day rally.

"We're going to take this fight across America, but we've got to defend the home front first," he added.

Protesters marched through parts of Chicago on Monday in a "Workers over Billionaires" rally that also saw people vocalize their opposition to Trump sending troops into the city.

by Michael Mathes