A Google director says he has resigned, citing the company's work with the US Department of Defense, Business Insider has learned.

René Mayrhofer, a director for Android platform security, wrote a farewell note to colleagues that was circulated internally and obtained by Business Insider. He said his decision to resign had become "unavoidable" after Google signed an agreement to let the Pentagon use its AI models for classified work.

"Google management has quietly abandoned the goals to become carbon-neutral because of the AI model energy usage," he wrote in the note, titled "Google Management Has Lost Its Moral Compass" and dated May 18. "Worse, the current Google management is now signing deals with the US Ministry of War—where 'any lawful purpose' by the current US government has already been repeatedly demonstrated to be in violation of international laws."

Mayrhofer confirmed the authenticity of the letter to Business Insider and said that, while there are "very good people left" on his team, he "can't/won't personally align with the overall company direction" of working with the US military.

Google said in late April that it had signed a deal with the Department of Defense to provide its AI technology for classified work, which can include tasks such as planning military operations and intelligence gathering. The decision led to backlash among some of the workforce, some of whom had previously urged leaders not to sign the agreement.

Google did not respond to a request for comment. A spokesperson previously told Business Insider the company was "proud" to be part of a consortium of AI labs providing AI services "in support of national security."

"We remain committed to the private and public sector consensus that AI should not be used for domestic mass surveillance or autonomous weaponry without appropriate human oversight," they said.

'I am a pacifist'

In his farewell letter, which Mayrhofer later posted on his personal blog, he referred to the AI principles Google drew up in 2018. They included a pledge not to use AI to develop weapons or surveillance tools. In February 2025, Google updated its guidelines to remove those restrictions.

Mayrhofer said Google offered him the job in 2017, but said that "times have changed" at the company since then, citing what he sees as a lack of transparency around some of the company's decisions.

"None of this is being debated or communicated within the company," Mayrhofer wrote, adding that decisions are "just being decided by top-level management."

Mayrhofer is not the first Google employee to publicly voice disagreement over the company's Pentagon deal. Andreas Kirsch, a research scientist at Google DeepMind working on AI, told Business Insider in April that he was "incredibly ashamed" of Google's decision to provide its AI for classified work.

"I am a pacifist, and have long ago decided that I will not personally work for militaries engaging in offensive warfare (strictly defensive action is somewhat more nuanced)," Mayrhofer wrote in his note. "Proactively harming people is not something that I can or will be involved with."

Mayrhofer, who is also an academic at Johannes Kepler University Linz (JKU), Austria, said he believes the US government "has become hostile" to educational institutions. Citing a Politico report that a Belgian university warned staff about collaborating with US colleges, Mayrhofer said he was concerned that Google's Pentagon deal to use AI for "any lawful purpose" could include mass surveillance of EU citizens.

"This deal implies that Google (AI) products will likely be used directly against me and mine. In this recent environment, I don't see how I could not resign."

In his message to Business Insider, Mayrhofer said he did not blame team members for not leaving for the same reasons as him.

"I am aware that, as a tenured academic in the EU, I am quite privileged that my decision to leave was only hard because I was balancing the good I could still do within Android security vs. tolerating the military angle, but not being dependent on the financial part of the employment. Many others are not in that situation," he said.

Mayrhofer said in his resignation note that while he would be serving his notice period at the company until August, he would "immediately disconnect from any work on AI systems that might fall under this deal with the DoW."

"I am quite sad that it had to come to this, and desperately hope Google management re-discovers its moral compass," he wrote. "Until then, I'll miss y'all."