Elon Musk says he plans to sue Apple for allegedly excluding his social media platform X and its AI chatbot app Grok from the App Store’s featured app sections.

Late Monday, Musk posted on X questioning Apple’s decision: “Hey @Apple App Store, why won’t you include X or Grok in your ‘Must Have’ section when X is the #1 news app globally and Grok ranks #5 overall? Are you playing politics?”

Grok is developed by Musk’s AI company, xAI.

Musk accused Apple of creating conditions that prevent any AI company other than OpenAI from reaching the top of the App Store rankings, calling it a “clear antitrust violation.” He said xAI would pursue legal action immediately, though he didn’t provide specifics.

Apple has not yet responded publicly.

This comes amid ongoing scrutiny of Apple’s App Store practices. A U.S. federal judge recently ruled that Apple violated an injunction in an antitrust lawsuit filed by Fortnite developer Epic Games.

In Europe, the EU fined Apple €500 million earlier this year for restricting app developers from directing users to cheaper payment options outside of the App Store. In a separate case last year, the EU also fined Apple nearly $2 billion for favoring its own music service over rivals like Spotify.

As of Tuesday morning, Apple’s top apps included TikTok, Tinder, Duolingo, YouTube, and Bumble, with ChatGPT from OpenAI ranking seventh.