Hundreds of employees at Google and OpenAI have signed an open letter urging their companies to stand with Anthropic in its standoff with the Pentagon over military applications for AI tools like Claude.

The letter, titled “We Will Not Be Divided,” calls on the leadership of both companies to “put aside their differences and stand together to continue to refuse the Department of War’s current demands for permission to use our models for domestic mass surveillance and autonomously killing people without human oversight.” These are two lines that Anthropic CEO Dario Amodei has said should not be crossed by his or any other AI company.

As of publication, the letter has over 450 signatures, almost 400 of which come from Google employees and the rest from OpenAI. Currently, roughly 50 percent of all participants have chosen to attach their names to the cause, with the rest remaining anonymous. All are verified as current employees of these companies. The original organizers of the letter aren’t Google or OpenAI employees; they say are unaffiliated with any AI company, political party or advocacy group.

The open letter is the latest development in the saga between Anthropic and US Defense Secretary Pete Hegseth, who threatened to label the company a “supply chain risk” if it did not agree to withdraw certain guardrails for classified work. The Pentagon has also been in talks with Google and OpenAI about using their models for classified work, with xAI coming on board earlier this week. The letter argues the government is "trying to divide each company with fear that the other will give in.”

OpenAI CEO Sam Altman told his employees on Friday that the ChatGPT maker will draw the same red lines as Anthropic, according to an internal memo seen by Axios. He told CNBC on the same day that he doesn't "personally think the Pentagon should be threatening DPA against these companies."