WASHINGTON — Chad F. Wolf, the acting secretary of homeland security, on Thursday defended his deployment of tactical agents to face protesters in Portland, Ore., after the standoff prompted accusations that the operation had politicized his agency.
Mr. Wolf told the Senate Homeland Security Committee that the local government in Portland had created a security void at the federal courthouse there, forcing him to deploy agents from Immigration and Customs Enforcement and Customs and Border Protection to support the Federal Protective Service, which provides year-round security at the courthouse.
The tactical teams provoked a national backlash after they used tear gas on crowds and detained protesters in unmarked vehicles. While the agents in front of the courthouse have been replaced with state police officers, Mr. Wolf said the tactical agents would remain in Portland until the agency was satisfied that the violence had subsided.
Mr. Wolf and Gov. Kate Brown of Oregon, a Democrat, agreed last week to replace the federal agents in front of the courthouse with state police officers.
“The full-augmented D.H.S. law enforcement posture remains in Portland,” Mr. Wolf told senators. “They will continue to remain until we are assured that the Hatfield federal courthouse, as well as other federal facilities in Portland, will no longer be violently attacked.”
In the days since federal agents pulled back, the crowd sizes have reduced to hundreds from thousands, and protests have moved away from the courthouse. On Wednesday night, the protests continued, with a crowd showing up at the Portland police bureau’s east precinct, spray-painting surveillance cameras and smashing the glass front doors. The police pursued the protesters through the streets, at times using tear gas despite local restrictions against it. Eight people were arrested.
Senate Democrats admonished Mr. Wolf for the deployment, saying that federal agents, including U.S. marshals, had only escalated tensions. They questioned why such agents would employ tactics so aggressive that the inspectors general of the Departments of Justice and Homeland Security have opened investigations.
Republicans used images of protesters pointing lasers at federal officers and lobbing commercial-grade fireworks and bottles at the courthouse to back the deployment. Mr. Wolf said 277 homeland security agents were injured from July 4 to July 31, with injuries ranging from minor wounds to serious eye damage.
Videos have also captured agents clubbing a Navy veteran who stood peacefully and firing rubber bullets at demonstrators. Senior Homeland Security Department officials have attributed those episodes to the U.S. Marshals.
Senator Kamala Harris of California, who is being considered for the Democratic vice-presidential nomination, pressed Mr. Wolf on the use of force against journalists and legal observers, which is now the subject of litigation, as well as the tear-gassing of demonstrators. The crowds have included lines of veterans and mothers protesting peacefully.
“Have you consulted with medical experts about the impact of chemical irritants on protesters, including pregnant women?” Ms. Harris asked.
Mr. Wolf said he had not examined the effect specifically on pregnant women. He then tried to differentiate between the crowds gathered during the day, which he described as overwhelmingly peaceful, and those that he said were more violent after midnight. Videos have also captured the line of mothers outside the courthouse after midnight.
“I would advise you,” Ms. Harris pressed, “it is well known there are mothers, including pregnant women, attending these protests. I would advise you to consult with medical experts.”
Mr. Wolf said no agents had been suspended for excessive force.
And he called criticism from his predecessors, including Michael Chertoff, a homeland security secretary under George W. Bush, “dead wrong.” Those critics have said the department should have worked harder to collaborate with local officials before deploying the agents.
“I’m not going to get into an argument,” Mr. Chertoff said, adding that he based his views on videos capturing the unrest and that he was still concerned that President Trump was using the department for political purposes.
Mr. Wolf and Mark Morgan, the acting commissioner of Customs and Border Protection who spoke at a separate media briefing, continued to push back against criticism over the agents wearing camouflage uniforms as they detained demonstrators on Portland’s streets. Mr. Morgan pointed out that the uniforms were labeled “POLICE,” although even some administration officials have described the uniforms as ambiguous.
Kenneth T. Cuccinelli II, the acting deputy secretary of homeland security, submitted remarks to a Senate committee this week saying the department would “rapidly” replace the uniforms. Mr. Morgan provided clarity on Thursday: The agency is changing the color of the uniforms from camouflage to green.
Mike Baker contributed reporting from Seattle.