Businessman Elon Musk is declaring “war” on a marketing industry trade group that he claims, in a federal antitrust lawsuit filed on Tuesday, was behind a discriminatory ad boycott of his social media platform, X. 

“We tried peace for 2 years, now it is war,” Mr. Musk wrote on X, sharing an announcement of the lawsuit posted by X Corp.’s chief executive, Linda Yaccarino. 

In the statement, Ms. Yaccarino accuses the Global Alliance for Responsible Media of coordinating an “illegal boycott” with other brands and advertising agencies against X, costing the social media platform “billions of dollars.” 

“The consequence — perhaps the intent — of this boycott was to seek to deprive X’s users, be they sports fans, gamers, journalists, activists, parents or political and corporate leaders, of the Global Town Square,” she adds. 

The group at the center of the controversy was created by the World Federation of Advertisers in 2019 “to help the industry address the challenge of illegal or harmful content on digital media platforms and its monetization via advertising,” according to its website. 

The lawsuit, filed in northern Texas, also calls out the roughly 100 members of the Global Alliance for Responsible Media, including CVS Health, Mars, Orsted, and Unilever, accusing them of conspiring, “along with dozens of non-defendant co-conspirators, to collectively withhold billions of dollars in advertising revenue from Twitter, Inc.”

The suit’s filing comes just weeks after the House Judiciary Committee released a report claiming that large media companies “participated in boycotts and coordinated action to demonetize platforms, podcasts, news outlets, and other content” that the Global Alliance for Responsible Media and its members “deem disfavored.” 

In addition to X, victims of the group’s “anti-conservative bias,” the report alleges, include conservative media outlets such as the Daily Wire, Fox News, and Breitbart. 

“The information uncovered to date regarding WFA and GARM’s collusive conduct in demonetizing disfavored content is alarming,” the committee noted, adding that it will “continue its investigation into companies involved in this conduct to inform potential legislative reforms.” 

In her statement, Ms. Yaccarino also suggested that there are likely other victims of the boycott, writing, “This case is about more than damages — we have to fix a broken ecosystem that allows this illegal activity to occur.”

Mr. Musk has since called for “any company who has been systematically boycotted by advertisers to file a lawsuit,” he wrote in a post on X. 

The billionaire businessman is no stranger to conflict with advertisers. After Mr. Musk was accused of posting what appeared to be an antisemitic comment on X, several major brands including Disney, Warner Bros, and Discovery paused their marketing campaigns on X in retaliation. 

Mr. Musk subsequently accused the companies of being “evil” and denounced them for using his social media platform for marketing purposes if they are just going to “blackmail me with advertising.”

Mr. Musk has faced criticism for failing to do enough, as some watchdog groups contended, to monitor and remove antisemitic content on the social media platform.

In response to such criticism, Mr. Musk recently sued “a group of independent researchers,” the Center for Countering Digital Hate, “whose research documented an increase in hate speech” on X, the Associated Press reported, but the suit was dismissed in March.