Sen. Rand Paul (R-KY) on Monday spoke out against the Trump administration’s use of federal force against protesters in Portland, warning that U.S. citizens “cannot give up liberty for security.”

“We cannot give up liberty for security. Local law enforcement can and should be handling these situations in our cities, but there is no place for federal troops or unidentified federal agents rounding people up at will,” Paul said following last week’s reports of federal agents detaining protesters in unmarked police vehicles:

Paul’s remark follows President Trump vowing to quell violence in cities “run by very liberal Democrats.”

“Look at what’s going on. All run by Democrats. All run by very liberal Democrats. All run really by [the] radical left. We can’t let this happen in the cities,” Trump told reporters on Monday in response to reports of the Department of Homeland Security moving to deploy roughly 150 agents to Chicago as homicide rates continue to surge in the city.

Last week, federal law enforcement officers took to the streets in Portland, which has remained under siege from violent protesters for several weeks, reportedly detaining protesters in unmarked police vehicles:

According to Oregon Public Broadcasting (OPB), federal officers have been using unmarked vehicles to detain protesters since “a least” July 14, following weeks of protesters attacking cops, vandalizing federal buildings, and repeatedly attempting to light police precincts on fire.

“What is going on? Who are you?” one woman asks in a video showing two officers in camo escorting an individual to an unmarked vehicle.

“You just violated their rights,” one witness said as another accused them of “kidnapping people.” The reports sparked outrage from many on social media, some of whom described the action as “state terror.”

Portland Mayor Tom Wheeler (D), who has been unable to quell the violence plaguing his city — violence which has resulted in the loss of $23 million by area-businesses — criticized the administration’s intervention, proclaiming that it is “making the situation much more dangerous.”

“I’m worried that one of our residents, or one of our local and state law enforcement officers, is going to get killed because of the tactics that they’re currently engaged in,” he said, contending that the unrest was “way down” prior to the federal law enforcement’s involvement.

“Violence was way down, vandalism was way down, local and state law enforcement had contained the situation. The energy was coming out of the demonstrations. We had hoped that they would end within a matter of days,” he continued.

Wheeler told CNN’s Jake Tapper that the administration is using “abhorrent” and “unconstitutional” tactics and added that their presence “is actually leading to more violence and more vandalism.”

“And it’s not helping the situation at all. They’re not wanted here. We haven’t asked them here. In fact, we want them to leave,” he said.

President Trump defended the decision on Sunday:

We are trying to help Portland, not hurt it. Their leadership has, for months, lost control of the anarchists and agitators. They are missing in action. We must protect Federal property, AND OUR PEOPLE. These were not merely protesters, these are the real deal!

The city saw yet another night of unrest late Sunday. Portland moms created a “human shield” as part of an effort to defend protesters, who ultimately tore down the fence around the courthouse and committed acts of arson, prompting federal officers to respond.

The Portland Police Bureau said in a statement that its officers “were not present during any of the activity described” and “did not engage with any crowds and did not deploy any CS gas.”

Oregon officials have since taken legal action against the federal government over its intervention.

“Oregon Attorney General Ellen Rosenblum late Friday sued Homeland Security and the Marshals Service in federal court,” the AP reported. “The complaint says that unidentified federal agents have grabbed people off Portland’s streets ‘without warning or explanation, without a warrant, and without providing any way to determine who is directing this action.'”