Elon Musk’s social media platform X has sued a group of advertisers, alleging that a “massive advertiser boycott” deprived the company of billions of dollars in revenue and violated antitrust laws.

The company formerly known as Twitter filed the lawsuit Tuesday in a federal court in Texas against the World Federation of Advertisers and member companies Unilever, Mars, CVS Health and Orsted.

It accused the advertising group’s initiative, called the Global Alliance for Responsible Media, of helping to coordinate a pause in advertising after Musk bought Twitter for $44 billion in late 2022 and overhauled its staff and policies.

Musk posted about the lawsuit on X on Tuesday, saying “now it is war” after two years of being nice and “getting nothing but empty words.”

X CEO Linda Yaccarino said in a video announcement that the lawsuit stemmed in part from evidence uncovered by the U.S. House Judiciary Committee which she said showed a “group of companies organized a systematic illegal boycott” against X.

The Republican-led committee had a hearing last month looking at whether current laws are “sufficient to deter anticompetitive collusion in online advertising.”