Elon Musk says that Twitter is in “clear material breach” of their $44 billion acquisition deal and that he could “terminate” the agreement in response. In a letter sent to Twitter this morning, Musk’s legal team claims that Twitter has failed to provide him with information on the service’s spam bot problem and that he’s entitled to receive that information under the deal agreement.

“Mr. Musk believes the company is actively resisting and thwarting his information rights (and the company’s corresponding obligations) under the merger agreement,” the lawyers write. The letter says Musk could choose “not to consummate the transaction” because of the alleged breach of contract.

Musk has spent weeks complaining about the spam bot problem on Twitter in what has appeared to be a strange effort to escape a deal he signed barely more than a month ago. Musk tweeted that the deal was “on hold” due to his concerns around bots and said the deal “cannot move forward” until Twitter proves the accuracy of its spam counts.

But it wasn’t until today that Musk made an official threat to back out of the deal, with most of his prior complaints being made in tweets and interviews. Wedbush Securities analyst Daniel Ives wrote this morning that the letter indicates Musk is “looking to walk away from [the] deal.” Twitter did not immediately respond to a request for comment.

Twitter estimates that less than 5 percent of its daily users are spam accounts. Last month, Twitter CEO Parag Agrawal said the company had provided Musk with an explanation of how Twitter generates its spam estimates. “We shared an overview of the estimation process with Elon a week ago,” Agrawal wrote in mid-May, “and look forward to continuing the conversation with him, and all of you.”