Most of the staff at OpenAI have threatened to resign from the company and join Microsoft, which has hired ousted OpenAI CEO Sam Altman and former OpenAI co-founder Greg Brockman to lead a new “advanced AI research team.” In a letter to OpenAI’s board that was reported on this morning by Wired and journalist Kara Swisher, more than five hundred current OpenAI staffers say that “Microsoft has assured us that there are positions for all OpenAI employees at this new subsidiary should we choose to join.”

The letter says the OpenAI employees will resign if the board does not reinstate Altman and Brockman and then resign. But seeing as the board has already made its choice, deciding to remain in place and naming a new CEO, while Altman and Brockman head to Microsoft, it seems that Microsoft may have just found Altman’s first several hundred employees, assuming they’re correct about the company’s promise to hire them all.

OpenAI employees signing the letter accuse the company’s board of jeopardizing their work and having “undermined our mission and company.” They also reject the idea that OpenAI was pushing ahead too quickly without concern for safety. “Our work on AI safety and governance shapes global norms,” they write.

Swisher reports that there are currently 700 employees as OpenAI and that more signatures are still being added to the letter. The letter appears to have been written before the events of last night, suggesting it has been circulating since closer to Altman’s firing. It also means that it may be too late for OpenAI’s board to act on the memo’s demands, if they even wished to do so.

Microsoft has created a special “advanced AI research team” to house a number of former OpenAI employees, with Sam Altman offered a CEO title to lead the division. It’s an unusual move for Microsoft outside of acquisitions, as the company typically only uses the CEO title for the leaders of big divisions like Microsoft Gaming, or acquired companies like LinkedIn and GitHub. OpenAI employees have made it clear that Microsoft is treating this like a big acquisition, assuring existing employees that there are open roles to join Sam Altman and his team at Microsoft.

Altman’s hiring came just hours after negotiations with OpenAI’s board failed to bring him back as OpenAI CEO over the weekend. Instead, former Twitch CEO and co-founder Emmett Shear has been named as interim CEO. He will take over from Mira Murati, who was named interim OpenAI CEO following Altman’s shock firing on Friday. Murati is at the top of the list of OpenAI employees threatening to now join Microsoft.

Microsoft’s new advanced AI research team, led by Altman and Brockman, comes just a week after Microsoft announced it has built its own custom AI chip that can be used to train large language models and potentially avoid a costly reliance on Nvidia. Altman had been reportedly pitching a separate startup to build custom, Nvidia-rivaling AI Tensor Processing Unit (TPU) chips to investors recently, according to The New York Times.