President Donald Trump said Monday that he may send federal law enforcement officers to Philadelphia and other cities with Democratic mayors. That followed his administration’s controversial deployment of federal agents to respond to protests in Portland, Ore., which has included reports of authorities using unmarked vehicles to grab protesters off the street without explanation.

But in trying to justify the expansion of such deployments, Trump has conflated regular crime, such as the high number of shootings in Chicago last weekend, with peaceful protests over the police killing of George Floyd in Minneapolis.

Democrats as well as conservative Trump critics have decried the actions as election-year stunts and an abuse of power.

“I’m going to do something — that I can tell you,” Trump said Monday. “Because we’re not going to let New York and Chicago and Philadelphia and Detroit and Baltimore and all of these — Oakland is a mess. We’re not going to let this happen in our country. All run by liberal Democrats.”

Here’s what you need to know:

What is Trump threatening to do?

Trump was not specific about which federal agents he might send to Philadelphia, and for what purpose.

In Portland, Border Patrol agents were deployed on the ground of protecting federal property and employees from protesters. A viral video of camouflaged officers seizing a protester and taking him away in an unmarked minivan led to outcry over tactics criticized as reminiscent of authoritarian regimes.

Protests in Portland have remained heated, and the administration has selectively highlighted incidents there. But the protests in Philadelphia and other cities have been almost entirely peaceful for weeks.

In Chicago, the administration is sending about 150 Homeland Security Investigations agents, in part to assist with enforcing regular criminal law unrelated to the protests, such as shootings.

It remains to be seen what, if anything, the administration will actually do in Philadelphia.

How is what’s happening in Philadelphia different from Portland?

In Philadelphia, the protests against police brutality have remained peaceful for more than a month, following a tumultuous first week that also saw significant looting and arson. That’s different than in Portland, where protesters have massed downtown for more than 50 days.

Even in Portland, the protests have been largely peaceful. Much of the evidence of violent behavior that federal authorities have cited regards property damage, including graffiti on a federal courthouse and a fire at a police union office. Local officials have said the demonstrations were growing smaller and less tense until federal law enforcement arrived, escalating tensions.

Trump has used recent spikes in crime in Chicago to justify sending agents there. Homicides have also increased sharply this year in Philadelphia. Three people were fatally shot between Monday night and early Tuesday morning, police said, bringing the city’s year-to-date homicide total to 230 — close to the 248 who were killed in all of 2014.

Other violent crimes, including rapes, robberies, and aggravated assaults not involving guns, have fallen.

Is Trump allowed to send federal agents to Philadelphia?

The administration has cited 40 U.S. Code 1315 under the Homeland Security Act of 2002, which gives the department’s secretary the power to deploy agents to protect federal property, as justification for sending officers to Portland. Now Trump is using that same rationale to threaten to send agents to other cities — something local legal experts say would be unprecedented and possibly unconstitutional.

”It’s a stretch to begin with,” said Anil Kalhan, a Drexel University law professor.

”The rhetoric is basically labeling people who are fellow citizens as domestic enemies and then deploying these paramilitary forces to aggressively engage in a show of force against them,” Kalhan said. “There are serious, substantive legal concerns with these activities.”

Alexis Karteron, a Rutgers University associate professor of law and director of the school’s Constitutional Rights Clinic, called the administration’s reasoning “very dubious.”

”I can’t think of any legitimate reason to be sending federal law enforcement to Philadelphia right now,” Karteron said. “Federal troops descending on American cities, that is very troubling, outside of historic practices, and almost certainly illegal.”

What are federal agents allowed to do if Trump sends them?

When federal agents are deployed to protect federal property, they have limited authority, experts said. They may only make an arrest without a warrant for a crime committed in their presence and if they have reasonable grounds to believe it is a felony, Kalhan said.

”They don’t have generalized authority to engage in domestic law enforcement,” Kalhan said.

The actions of federal law enforcement in Portland have already led to lawsuits alleging civil rights violations.

How have local officials responded to Trump’s threat?

Mayor Jim Kenney on Tuesday dismissed Trump’s stated concerns about public safety as disingenuous given the administration’s inaction in the early stages of the coronavirus pandemic, which hit urban centers hardest.

“If the Trump administration wanted to help cities, they would have gotten off their rear ends back in March and April,” Kenney said. “This is a game he’s playing to divert attention away from the many crises that are facing this nation, and we’ll oppose it with everything we have.”

Philadelphia District Attorney Larry Krasner compared Trump’s threat to fascism.

“My dad volunteered and served in World War II to fight fascism, like most of my uncles, so we would not have an American president brutalizing and kidnapping Americans for exercising their constitutional rights and trying to make America a better place, which is what patriots do,” he said in a statement. “Anyone, including federal law enforcement, who unlawfully assaults and kidnaps people will face criminal charges from my office.”

U.S. Sen. Pat Toomey (R., Pa.) dodged the question of whether Trump should send federal officers to Philadelphia and instead joined in attacking the city’s Democratic leaders.

“The rioting, violence, and lawlessness in Portland is a disgrace, and I hope it does not happen in Philadelphia,” Toomey said. “One way to ensure that it does not is for Philadelphia’s mayor and district attorney to actually support the police, enforce the law, and hold criminals accountable.”

U.S. Sen. Bob Casey (D., Pa.) said Trump’s “secret police are kidnapping and holding citizens without charges for exercising their constitutionally-guaranteed rights.”

“This is totalitarianism,” Casey said. ”Law enforcement should protect the people — not the president’s self-interested political motives. ... This unconstitutional paramilitary force has no place anywhere in a healthy democracy and, considering Philadelphia’s historical significance as the birthplace of our Constitution, it would be especially disrespectful and insulting here.”

What happens next?

The Trump administration is reportedly deploying the HSI agents to Chicago this week.

It’s unclear if Trump will follow through on his threats regarding the other cities, which he made while speaking off the cuff with reporters. He also mentioned Detroit, Baltimore, and Oakland, Calif., casting the issue in explicitly political terms.

“Look at what’s going on — all run by Democrats, all run by very liberal Democrats,” he said. “All run, really, by radical left.

“If Biden got in, that would be true for the country,” Trump added. “The whole country would go to hell. And we’re not going to let it go to hell.”

Staff writer Jonathan Tamari contributed to this article.