The company said in a statement Thursday that the ads violated "our policy against organized hate." A Facebook executive who testified at a House Intelligence Committee hearing on Thursday said the company does not permit symbols of hateful ideology "unless they're put up with context or condemnation."
"In a situation where we don't see either of those, we don't allow it on the platform and we remove it. That's what we saw in this case with this ad, and anywhere that that symbol is used, we would take the same action," said Nathaniel Gleicher, the company's head of security policy.
The Trump campaign spent more than $10,000 on the ads, which began running on Wednesday and targeted men and women of all ages across the U.S., though primarily in Texas, California and Florida.
In a statement, Trump campaign communications director Tim Murtaugh said the inverted red triangle was a symbol used by antifa so it was included in an ad about antifa. He said the symbol is not in the Anti-Defamation League's database of symbols of hate. The Trump campaign also argued that the symbol is an emoji.
"But it is ironic that it took a Trump ad to force the media to implicitly concede that Antifa is a hate group," he added.
Antifa is an umbrella term for leftist militants bound more by belief than organizational structure. Trump has blamed antifa for the violence that erupted during some of the recent protests, but federal law enforcement officials have offered little evidence of this.
The ADL disputed that the red triangle was commonly used as an antifa symbol. The organization said the triangle was not in its database because it is a historical symbol and the database includes only those symbols used by modern-day extremists and white supremacists.
"Whether aware of the history or meaning, for the Trump campaign to use a symbol - one which is practically identical to that used by the Nazi regime to classify political prisoners in concentration camps - to attack his opponents is offensive and deeply troubling," ADL chief executive officer Jonathan Greenblatt said in a statement.
The action comes as Facebook and other technology companies face persistent criticism, particularly from Democrats, about whether they are doing enough to police the spread of disinformation and tweets and posts from Trump perceived as inflammatory.
Those questions arose during Thursday's hearing when a Twitter representative was asked why the company flagged but did not remove tweets from the president, including one that raised the prospect of shooting looters during the recent unrest in American cities. Facebook, too, was asked why it did not remove a doctored video of House Speaker Nancy Pelosi, D-Calif., last year that appeared to show her slurring her words.
"If we simply take a piece of content like this down, it doesn't go away," Gleicher said. "It will exist elsewhere on the internet. People who are looking for it will still find it."
With Thursday's hearing focused on the spread of disinformation tied to the 2020 election, the companies said they had not yet seen the same sort of concerted foreign influence campaigns like the one four years ago, when a Russian troll farm sowed discord online by playing up divisive social issues.
But that suggests the threat has evolved rather than diminished, said the executives, who pointed out that media companies controlled by the state were directly and openly engaging online on American social issues to affect public opinion. China, for instance, has likened allegations of police brutality in the U.S. to the criticism it faced for its aggressive treatment of protesters in Hong Kong last year.
Preventing disinformation ahead of the election is a significant challenge in a country facing potentially dramatic changes in how people vote, with expected widespread use of mail-in ballots creating openings to cast doubt on the results and even spread false information.
Facebook said Thursday that it is working to help Americans vote by mail, including by notifying users about how to request ballots and whether the date of their state's election has changed.
The Vote By Mail notification connects Facebook users to information about how to request a ballot. It is targeted to voters in states where no excuse is needed to vote by mail or where fears of the coronavirus are accepted as a universal excuse.
"Providing that accurate information is one of the best ways to mitigate those kinds of threats," Gleicher said.