President Donald Trump is threatening to send federal agents to New York and other cities, signaling a possible expansion of the heavily-militarized crackdown on protesters seen in Portland in recent days.

During an impromptu press conference in the Oval Office on Monday, Trump promised "more federal law enforcement" in cities "run by liberal Democrats."

Echoing unfounded claims raised by NYPD Commissioner Dermot Shea and police union leaders that elected officials have blocked police officers from doing their jobs, Trump specifically pointed to New York City as a possible target.

"I know New York very well. I know the police very well. New York’s finest. The fact is they’re restricted from doing anything, they can’t do anything. I’m going to do something, that I can tell you," the president said.

Asked what specifically he planned to do, Trump replied: "We’re going to have more federal law enforcement, that I can tell you."

A spokesperson for Attorney General Letitia James told Gothamist that the office would mount a legal challenge against any attempt by the Trump administration to send federal troops after New York protesters.

Mayor Bill de Blasio also pushed back on the threat, saying in a statement that "New Yorkers and the NYPD know how to keep this city safe. What federal agents are doing in Portland is unacceptable and it has no place in New York."

On Thursday, video emerged of military-clad officers without visible identification snatching a protester off a Portland street and placing them in an unmarked vehicle. The agents, who were later identified as Customs and Border Patrol officers, continued to fire tear-gas and projectiles at protesters this weekend, significantly escalating tensions on the ground, according to local reporters.

On Saturday night, a Navy veteran was beaten and pepper sprayed by federal agents after he attempted to ask them if seizing civilian protesters violated their oath to defend the Constitution. The beating, which left the 53-year-old veteran with a broken hand, was caught on video.

"In Portland, they’ve done a fantastic job," Trump said Monday. "These people are anarchists. These are people who hate our country and we’re not going to let it go forward."

Chief of Department Terence Monahan, the NYPD's highest-ranking uniformed officer, also recently described demonstrators as violent anarchists, "whose sole purpose is to get rid of government." Commissioner Shea has falsely claimed that local activists are "outside agitators" — an allegation also used by Trump to discredit the Black Lives Matter movement.

The NYPD did not respond to questions about whether they would support federal agents helping to police protests in New York City.

In a phone interview, Sergeant Benevolent Association President Ed Mullins said he'd support the deployment of federal agents in New York City, claiming that officers were hamstrung by recent bail reform laws and legislation against chokeholds.

"If federal agents are coming in to assist the NYPD and take [alleged criminals] through federal court, where we know the U.S. Attorney’s Office will prosecute them, I think that’s a great idea,” said Mullins, an outspoken Trump supporter. "What we need is leadership here in New York. If the president wants to send leadership, that’s great."

A spokesperson for the Department of Homeland Security said she was not aware of existing plans to send federal DHS officers to New York City.

A memo prepared by Acting Secretary of Homeland Security Chad Wolfe, and obtained by the Times, seemingly anticipates future encounters between federal agents and protesters in other cities.

On Monday, sources told the Chicago Tribune that DHS was preparing plans to deploy roughly 150 federal agents to Chicago this week. Those plans have not been made public yet.