A request to Mr. Jones for comment was not immediately returned.
This is not the first time that Mr. Jones’s videos have received a strike from YouTube. In February, YouTube levied a strike for a video claiming that David Hogg, one of the outspoken student survivors of the school shooting in Parkland, Fla., was a “crisis actor.” YouTube said the video had violated its policies around harassment and bullying. But since there were no additional violations during the next 90 days, the strike was removed from the account.
Facebook and YouTube acted after weeks of controversy over Mr. Jones, who first gained notoriety by insisting that the terrorist attacks of Sept. 11, 2001, were an “inside job” by the United States government. Since then, he has questioned whether the 2012 massacre at Sandy Hook Elementary School was a hoax, promoted the so-called Pizzagate conspiracy theory and said fluoridated water was part of a government mind-control plot.
Despite these unsupported views, social media platforms have allowed him to gain a wide audience. Conservatives have accused Facebook, YouTube and other platforms of censoring right-wing views in the past, and have rallied behind him before.
This month, at a press event in New York about Facebook’s efforts to combat misinformation and false news, a reporter from CNN questioned company executives about why Infowars was still allowed to have a Facebook account. At the time, the company appeared unwilling to say Mr. Jones’s content violated its policies.
“Look, as abhorrent as some of this content can be, I do think that it gets down to this principle of giving people a voice,” Mark Zuckerberg, Facebook’s chief executive, said in a Recode podcast interview.
As an example, Mr. Zuckerberg cited Holocaust denial as a message that he found personally offensive but was wary of removing from Facebook, in order to protect users’ free-speech rights.
Within Facebook, the free-speech issues raised by Infowars and Mr. Jones have become an especially contentious topic. Employees have used internal chat forums to question executives about the site’s policies, according to one Facebook employee, who asked to remain anonymous because of fear of retribution. One group of Facebook workers, which included people of Jewish and Eastern European descent, raised Mr. Zuckerberg’s position on Holocaust denial with their superiors, saying they found it incomprehensible, according to the employee.