Anthropic's researcher Jacob Coxon, who worked on pretraining at both the company and OpenAI, said Wednesday that he had resigned Tuesday, saying neither company is "acting responsibly" as they race toward "self-improving superintelligence."

In a post on X, the researcher said these will soon be "superhuman systems that can hack anything, revolutionize any field overnight, and acquire real power and resources," and that "the people building AI earnestly believe that it could kill us all by the end of the decade."

He said that at OpenAI, "many have not deeply internalized the civilizational stakes," while at Anthropic, "the stakes are well-understood, but they are locked in a race to get there first" because they believe no one else will act responsibly.

The researcher said he remains "optimistic about the potential for coordination," citing warning shots such as the Hugging Face attack that have made pacing agreements between US labs "more viable," but said he does not feel the industry is "on track to prevent a global race."

Separately, OpenAI's chief scientist Jakub Pachocki wrote in a blog post published Sunday that no AI company has "solved alignment and monitoring to a sufficient degree to continue responsibly scaling at maximum speed for much longer."

Pachocki said he expects and hopes for "voluntary slowdowns to become commonplace until shared safety bars are established," and called for international coordination on AI development to become "a top priority for governments around the world."