Updated at 9:54 p.m. ET

Facebook on Thursday said it removed campaign posts and advertisements from the Trump campaign featuring an upside down red triangle symbol once used by Nazis to identify political opponents.

The posts, according to a Facebook spokesperson, violated the social network's policy against hate.

"Our policy prohibits using a banned hate group's symbol to identify political prisoners without the context that condemns or discusses the symbol," the spokesperson told NPR.

One of the political advertisements claimed that "dangerous MOBS of far-left groups are running through our streets and causing absolute mayhem." The ad went on to say protesters are destroying America's cities by rioting. "It's absolute madness," the ad said.

Some prisoners in Nazi concentration camps were identified with colored inverted triangles sewn onto uniforms to allow SS guards to identify the alleged grounds for being detained, according to the U.S. Holocaust Memorial Museum.

The Trump campaign responded by drawing a lighthearted comparison to the red triangle symbol: "This is an emoji."

Trump campaign spokesman Tim Murtaugh said that some products are sold online that use the inverted red triangle in antifa imagery, though experts said it is not a commonly adopted symbol among anti-fascist activists.

"We would note that Facebook still has an inverted red triangle emoji in use, which looks exactly the same, so it's curious that they would target only this ad," Murtaugh said.

The campaign also said that the symbol is not in the Anti-Defamation League Hate Symbols Database.

In an interview with NPR, Jonathan Greenblatt, CEO of the Anti-Defamation League, pointed out that the database is not a collection of historical Nazi imagery.

"It's a database of symbols commonly used by modern extremist groups and white supremacists in the United States," he said.

Greenblatt said removing the posts should not have been a hard call. He said the Trump campaign should apologize.

"Intentionally or otherwise, using symbols that were once used by the Nazis is not a good look for someone running for the White House," he said. "It isn't difficult for one to criticize a political opponent without using Nazi-era imagery."

Earlier Greenblatt had tweeted that "ignorance is no excuse for using Nazi-related symbols."

Facebook's action is the latest salvo between Trump and social media companies, which the president has attacked as biased for placing warning labels and removing posts that violate terms of service.

The removal of the Trump campaign's Facebook posts, which had already accrued more than a million impressions, was a rare move by the social network of more than 2.5 billion users, which has taken a permissive approach to most political advertisements.

"So in a way, it's kind of closing the barn door after all of the horses have gotten out of the barn," said Sarah Roberts, an assistant professor of information studies at UCLA who studies content moderation.

Roberts said for the Trump campaign, the advertisement is beneficial regardless of what Facebook's reaction.

"They get to circulate the ads for some period of time, and then they get to capitalize on a narrative that I believe to be demonstrably false, that they are somehow censored or impeded from sharing their perspectives on social media," Roberts said.

Unlike Twitter, which banned political ads and has added fact-checking labels to Trump tweets, Facebook has taken a more hands-off approach, with CEO Mark Zuckerberg doubling down on the influential social network's free speech absolutism. Zuckerberg has said it is not Facebook's job to determine what the truth is and that voting is the best way to hold elected leaders accountable.

According to the Facebook spokesperson, it is not the first time the platform has removed content from Trump in recent months. In March, Facebook took down advertisements from the Trump campaign that made misleading claims about the 2020 census. In other instances, though, such as in an ad in which Trump wrote of street protesters, "when the looting starts, the shooting starts," Facebook took no action.

The ADL's Greenblatt said his group has been urging Facebook to take a harder stance against intolerance on the platform.

"The one thing has been consistent with Facebook is the inconsistency," Greenblatt said. "It's hard to countenance how some things go up and stay up that are clearly egregious. They have an outsized role to play in the political conversation, and making sure they push prejudice out of the political conversation is not partisan. It's a matter of principle."

Facebook's move on Thursday comes as the Trump administration escalates its fight with Big Tech.

The Justice Department announced Wednesday that it was asking Congress to scale back some of the legal protections social media companies such as Facebook and Twitter have long enjoyed, arguing that the legal immunity granted to technology firms in the mid-1990s is out of step with the modern Internet.

But tech companies counter that rolling back the safeguards would impinge on free speech by forcing moderators to take down any content deemed offensive.

Supporters of keeping the legal shield in place also say eliminating the protections would disproportionately hurt smaller online operations, which could be crushed by a wave of defamation lawsuits.

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