President Donald Trump threatened Monday to send more military-garbed law enforcement into US cities to quell anti-racism protests, a move he called necessary security action and critics labelled an election year political stunt. After the Department of Homeland Security deployed scores of Border Patrol police and federal marshals -- many in combat fatigues -- to Portland, Oregon last week, Trump said he could do so in other Democrat-led cities. According to reports, DHS was preparing to send 150 paramilitary personnel to Chicago after police there clashed with demonstrators seeking to tear down a statue of Christopher Columbus. Separately, 63 people were shot and 12 killed over the weekend in ongoing gun violence, according to local media. "We're looking at Chicago, too. We're looking at New York," Trump told reporters. "Look at what's going on. All run by Democrats, all run by very liberal Democrats, all run really by radical left. We can't let this happen to the city." "I'm going to do something, that I can tell you, because we're not going to leave New York and Chicago and Philadelphia, Detroit and Baltimore," he said. In a statement, DHS said it "does not comment on any allegedly leaked operations." - Going to 'do our job' - But earlier, Homeland Security Acting Secretary Chad Wolf was defiant. "I don't need invitations by the state, state mayors or state governors to do our job. We're going to do that, whether they like us there or not," he said on Fox News. Trump's decision to have federal law enforcement authorities intervene in local protests has sparked anger and legal questions. Since African-American man George Floyd was killed by a Minneapolis police officer on May 25, sparking nationwide protests against racism and police brutality, Trump has sought to paint the demonstrators as radical leftists intent on destroying the country. Facing an uphill battle for reelection in November against Democrat Joe Biden, Trump is using the protests to rally support from his conservative base, Democrats say. Last week, Wolf said the Border Patrol and other officers were needed in Portland to stop "violent anarchists." But he accused protesters of minor crimes, such as breaking windows and putting graffiti on federal buildings. - 'Un-American' - After the DHS force arrived, video showed them taking some demonstrators away in unmarked vehicles. Most have been freed, but critics -- including Oregon's governor and senators -- likened it to "secret police" in more repressive societies. Oregon has sued DHS for rights violations, while the state's governor, Kate Brown, demanded the officers be withdrawn, calling the deployment a political "photo op." On Monday, the mayors of six major cities -- Atlanta, Washington, Seattle, Chicago, Portland and Kansas City -- said in a letter to Wolf and Attorney General Bill Barr that the uninvited paramilitary deployments violate the Constitution. "Deployment of federal forces in the streets of our communities has not been requested nor is it acceptable," they wrote. "It is concerning that federal law enforcement is being deployed for political purposes," they said. Michigan state Attorney General Dana Nessel called the threat to send federal officers to Detroit a threat to peace and the right to protest. "We are a nation of laws, and the President’s attempts to intimidate our communities with threats of violence could not be more un-American," she said.