This article has been updated.

After more than a week of unrest, tension in a number of major U.S. cities has eased. The vandalism and looting that had often used large, peaceful protests as cover have faded; the eruption of violence at protests appears to be less common. The Associated Press reports that active-duty members of the military who were moved into Washington to help keep order would be moved back out, though that decision was later reversed.

But it wasn’t only components of the Defense Department that had been brought to the nation’s capital to help with the “domination” that President Trump sought to display in the wake of the turmoil. Washington residents have also been confronted with a number of other heavily armed law enforcement officers who share an unexpected characteristic: Neither their affiliation nor their personal identities are discernible.

On Tuesday, Mother Jones reporter Dan Friedman encountered these individuals, who gave no more specific identification than that they were associated with the Justice Department.

Near the White House on Wednesday, MSNBC’s Garrett Haake had a similar encounter.

So did the New Republic’s Matt Ford. When he asked the armed men whether they were associated with the Bureau of Prisons based on an acronym on their uniforms, Ford was simply told, “Maybe.”

As it turns out, each of these encounters was apparently with elements of the Bureau of Prisons, called to the region by Attorney General William P. Barr this week. Friedman confirmed with the BOP that the men he encountered were with the agency; Haake’s Twitter followers picked out BOP insignia on their clothing.

“The idea that the federal government is putting law enforcement personnel on the line without appropriate designation of agency, name, etc. — that’s a direct contradiction of the oversight that they’ve been providing for many years to local police and demanding in all of their various monitorships and accreditation,” former New York City police commissioner William Bratton said in a phone interview with The Washington Post on Wednesday.

The prospect of government agencies involved in policing the city seeking to obscure their identities, Bratton said, was “very concerning.”

A strange moment on 16th Street NW in the District on Wednesday underscored the need for clarity. Authorities in blue shirts, black vests and no identifying markers stood watch, gripping riot shields emblazoned with the words “MILITARY POLICE.”

A representative of the National Guard confirmed that they were employees of the Bureau of Prisons. The officers were “backing up” the actual military police and used the shields left in place, said Army Lt. Col. Jamie Davis, a Guard spokesman.

“It’s a common tactic, but with marked shields like this, it can, and has, led to confusion,” he said.

This vagueness of identity and the officers’ lack of interest in identifying themselves introduce specific challenges and risks, as former Army officer and FBI special agent Clint Watts explained in a phone interview with The Post.

For one thing, Watts pointed out, a civilian might refuse to respond to an order from a law enforcement official who doesn’t identify themselves in that way.

“If I go out and I pull out a gun and I say, ‘Freeze,’ and they say why, I would have to say, ‘I’m an FBI agent’ or law enforcement officer or whatever,” he said, “because, otherwise, they would be totally in the right to defend themselves potentially.”

He imagined his own reaction if he were on the street in New York or Washington and an unidentified officer pushed him with a shield: His instinct would be to fight back.

The added danger, particularly given the influx of officials in the area, is that law enforcement officers wouldn’t recognize one another. Bratton noted that one reason for identifiers is that officers would be able to recognize one another. Riot helmets often have identifying numbers on their backs in part for that purpose.

Watts described an incident shortly after he began at the FBI when an undercover agent who had drawn his weapon was killed by another bureau employee who confused him with the perpetrator. Introduce scores of officers without identification into a volatile scenario and it’s easy to see similar (if less deadly) mistakes being common.

Particularly given another component of the moment. It’s not uncommon for civilians to dress in paramilitary gear and show up at the protests, often doing so as self-appointed assistants to police and other law enforcement officials.

“You can have this weird thing where you have these militia group guys just dressed up in their gear, which they like to do anyway, show up and just start pushing protesters around,” Watts said. “And if you’re a protester, you don’t know if you have to respond to this person.”

Granting unidentifiable law enforcement officials the ability to engage with and confront protesters functionally allows any unidentifiable individual to more easily pretend to be law enforcement. It introduces an opportunity for those looking to take advantage of the situation to target protesters or to cause disruptions.

The problem extends further. Consider the security guards hired to defend Saks Fifth Avenue’s flagship store in Manhattan.

It’s easy to envision a scenario in which protesters are confronted by other hired security and forced to determine in real time whether they constitute an official arm of law enforcement or whether they’re simply hired muscle. There are widely divergent ramifications for a protester’s potential responses to such confrontations, depending on who the other person is.

And there’s an overarching question here: Why? Why are these officers unwilling to identify themselves or their organization? There’s clearly some power dynamic at play, as demonstrated in the snide “maybe” Ford was offered. But it also inhibits accountability.

“If those officers engage in any type of misbehavior during the time that they are there representing the federal government, how are you to identify them?” Bratton said. “What is the need for anonymity in controlling crowd demonstrations?”

Such anonymity echoes the way in which enforcers in autocratic regimes have worked to avoid accountability. If you believe that you were unlawfully detained or assaulted by a law enforcement official, you can try to hold them to account. (Of course, the extent to which you’ll be able to do so is another question, one at the heart of the current protests.) But how do you hold someone accountable when you don’t know who they are or even who they work for?

Ruth Ben-Ghiat, a professor of history at New York University and an expert on authoritarianism, noted the lack of accountability introduced by the government of Chilean dictator Augusto Pinochet for the actions of loyalist forces.

“The government passed laws that allowed the service records of military men and police who had been involved in torture and abuses to be destroyed so that their records were swept clean,” she said. “Many authoritarian leaders issue amnesty that free service people, clean up their records so that their abuses are never known.”

The point isn’t necessarily that the lack of identification offered by the men in Washington is intended to facilitate abuse. It’s that it hampers accountability, intentionally or not, which itself makes abuse more likely to go unchecked. Officers of the law are accountable to the public, something that’s harder to achieve if you don’t know who they are.

What the current situation demands is clarity. Given the tension between law enforcement and the protesters and given the existence of those looking to amplify that tension either as cover for looting or to commit vandalism against the state, it seems more important now than it normally is that the enforcement arm of the government be identified by agency and individually.

“The idea of having no identification whatsoever as to the agency that you belong to,” Bratton said, “is highly unusual and, from my perspective, not professional at all.”

Haake updated his assessment of the scene at the White House on Wednesday afternoon, reporting that the unidentified officers had been replaced by members of the National Guard, in uniforms that included the D.C. flag.

But that didn’t last long.

Update: During a press briefing on Thursday, BOP Director Michael Carvajal addressed the issue.

“First of all, I’m not aware of any specific Bureau of Prisons personnel being told not to identify themselves,” he said. “What I attribute that to is probably the fact that we normally operate within the confines of our institution and we don’t need to identify ourselves. Most of our identification is institution-specific and probably wouldn’t mean a whole lot to people in D.C.”

“I probably should have done a better job of marking them nationally as the agency,” he added. “Point is well taken, but I assure you that no one was specifically told to my knowledge not to identify themselves.”

Alex Horton contributed to this report.