Elon Musk is threatening to take legal action against Microsoft over claims that the company “trained illegally using Twitter data.” The billionaire’s statement came in response to a tweet noting that Microsoft’s advertising platform announced it would stop supporting Twitter, reportedly due to Twitter’s changes requiring payment to access its API.

Musk’s threat is vague but appears to be over OpenAI using Twitter data to train the large language model behind products like ChatGPT. OpenAI, obviously, is not Microsoft, but it did recently receive a significant investment from the company, which is building AI into tools like Bing, Edge, and Microsoft 365.

It’s unclear whether Musk will actually sue Microsoft at this point, as he has threatened legal action that never happened in the past, including against the creator of the @ElonJet Twitter account.

Microsoft didn’t immediately respond to The Verge’s request for comment. Twitter’s press email replied with a poop emoji when reached for comment.

In a message on the top of a support page for Microsoft’s advertising platform, the company says it will “no longer support Twitter” starting on April 25th, 2023, which means companies can no longer use Microsoft’s platform to manage their tweets or engagement. This coincides with Twitter’s timeline to put its API (application programming interface) behind a paywall.

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