WASHINGTON — Beyond the car windows being smashed, people tackled on city streets — or even a little child with a floppy bunny ears snowcap detained — the images of masked federal officers has become a flashpoint in the Trump administration’s immigration enforcement operations.

Not in recent U.S. memory has an American policing operation so consistently masked its thousands of officers from the public, a development that the Department of Homeland Security believes is important to safeguard employees from online harassment. But experts warn masking serves another purpose, inciting fear in communities, and risks shattering norms, accountability and trust between the police and its citizenry.

Whether to ban the masks — or allow the masking to continue — has emerged as a central question in the debate in Congress over funding Homeland Security ahead of Friday’s midnight deadline, when it faces a partial agency shutdown.

“Humans read each others’ faces — that’s how we communicate,” said Justin Smith, a former Colorado sheriff who is executive director and CEO of the National Sheriffs’ Association.

“When you have a number of federal agents involved in these operations, and they can’t be identified, you can’t see their face, it just tends to make people uncomfortable,” he said. “That’s bringing up some questions.”

Masks on federal agents have been one constant throughout the first year of President Donald Trump’s mass deportation operation.

What began as a jarring image last spring, when plain-clothed officers drawing up their masks surrounded and detained a Tufts University doctoral student near her Massachusetts home, has morphed into familiar scenes in Los Angeles, Chicago and other cities. The shooting deaths of two American citizens at the hands of federal immigration officers during demonstrations against ICE raids in Minneapolis sparked widespread public protest and spurred lawmakers to respond.

“Cameras on, masks off” has become a rallying cry among Democrats, who are also insisting the officers wear body cameras as a way to provide greater accountability and oversight of the operations.

House Democratic Leader Hakeem Jeffries told reporters at the Capitol that unmasking the federal agents is a “hard red line” in the negotiations ahead.

Immigration and Customs Enforcement says on its website that its officers “wear masks to prevent doxing, which can (and has) placed them and their families at risk. All ICE law enforcement officers carry badges and credentials and will identify themselves when required for public safety or legal necessity.”

Fueled with funds from the Trump’s big tax cuts bill, which poured some $170 billion into Homeland Security, ICE has grown to become among the largest law enforcement operations in the nation. Last year, it announced it had more than doubled its ranks, to 22,000, with rapid hiring — and $50,000 signing bonuses. Homeland Security did not respond to an emailed request for further comment.

Most Republicans say the current political climate leaves the immigration officers, many of them new to the job, exposed if their faces and identities are made public.

Sen. Thom Tillis, R-N.C., said he just can’t agree with Democrats’ demand that officers unmask themselves.

“You know, there’s a lot of vicious people out there, and they’ll take a picture of your face, and the next thing you know, your children or your wife or your husband are being threatened at home,” he said. “That’s just the reality of the world that we’re in.”

It appears no other policing agency in the country regularly uses masking on a widespread basis. Instead, masks are used during special operations, particularly undercover work or at times during large crowd control or protest situations, and when there is inclement weather or individual health concerns.

Experts said only perhaps during the Ku Klux Klan raids or in the Old West has masking been a more widely used tool.

“It is without precedent in modern American history,” said the American Civil Liberties Union’s Naureen Shah in Washington.

She said the idea of masked patrols on city streets seeking immigrants can leave people scared and confused about who they are encountering — which she suggested is part of the point.

“I think it’s calculated to terrify people,” she said. “I don’t think anybody viscerally feels like, OK, this is something we want to become a permanent fixture in our streets.”

Toward the end of the first Trump administration, Congress sought to clamp down after masked federal agents showed up in 2020 to quell protests in Portland and other cities. A provision requiring agents to clearly identify themselves was tucked into a massive defense authorization bill that Trump signed into law.