Donald Trump announced plans to send National Guard troops to Chicago, continuing a pattern of federal deployments aimed at cities governed by Democrats.

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 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 hellhole right now. Baltimore is a hellhole 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 (Washington)."

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Anti-Trump protesters stage demonstrations in Washington as lawmakers return from summer recess / © GETTY IMAGES/AFP

"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 over the deployment, accusing the president of preparing "an invasion."

"Chicago does not want troops on our streets," the Democratic governor said at a press conference on Tuesday.

"Crime is down in Chicago. Murders are down by almost 50 percent in the last four years," he said.

"None of this is about fighting crime or making Chicago safer," Pritzker added. "For Trump, it's about testing his power and producing a political drama to cover up for his corruption."

- President as police chief? -

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Illinois Governor JB Pritzker / © AFP

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.

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Protesters opposed to federal troop deployments in Chicago march in the city / © AFP

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.

rotesters 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.