After the attack on Sam Altman, anti-AI groups took center stage. I took a closer look at two of them

Pause AI and Stop AI say they reject violence—but the full picture is more complicated.

Holly Elmore, founder and executive director of PauseAI US, at a recent demonstration on Capitol Hill. Courtesy of Pause AI US

Since the attempted firebombing on OpenAI CEO Sam Altman’s San Francisco home on April 10, AI backlash has been impossible to miss. You know it’s reached a moment when people are even mad at the hard-to-be-mad-at Reese Witherspoon for supporting some use of AI.

But as any terminally online AI industry watcher knows (myself included), anti-AI groups have been part of the conversation for years. I’ve covered the rising use of the word “doomer” since mid-2023, when I wrote this story for VentureBeat about AI experts challenging the ‘doomer’ narrative, including claims of a risk of human extinction from advanced AI if its development is not properly managed.

In that piece, many told me this 'doomsday' take, with its focus on existential risk from AI, or x-risk, is happening to the detriment of a necessary focus on current, measurable AI risks — including bias, misinformation, high-risk applications and cybersecurity. The truth is, most AI researchers are not focused on or highly-concerned about x-risk, they emphasized.

In a separate Q&A for VentureBeat in June 2023, top AI researcher Kyunghun Cho put it more bluntly, saying “I’m disappointed by a lot of this discussion about existential risk; now they even call it literal “extinction.” It’s sucking the air out of the room.”

Of course, these days, whether they are “doomers” or not, people are concerned about every kind of AI risk — from advanced cyber attack capabilities and deepfakes to predictions of massive job loss and the effect of mega AI data center construction on local communities. And while social media was filled with concern for Altman’s safety after the attempted firebombing allegedly carried out by 20-year-old Daniel Moreno-Gama, the action has drawn attention to two anti-AI groups with similar names: Pause AI and Stop AI. I had heard of both, but I dug into their histories and tactics for a Fortune story this week.

Both organizations have condemned the violence and said the suspect is not and never was a member of their organizations. Still, the incident, in which Moreno-Gama also went to OpenAI’s headquarters and tried to shatter the building’s glass doors with a chair and threatened to burn the facility, surfaced his activity on Pause AI’s Discord server and renewed scrutiny of Stop AI’s direct actions targeting OpenAI last year.

I hope you’ll consider reading the whole thing: This is a gift link. But here are a few details that stood out:

• The alleged attacker had posted 34 messages in Pause AI’s public Discord—including one saying, “we are close to midnight, it’s time to actually act”—but the group says none explicitly called for violence.

• Pause AI says it actively vets volunteers and tightly controls messaging to avoid being associated with extreme views.

• The group’s name traces back to the Future of Life Institute’s 2023 open letter calling for a pause on advanced AI—and that organization is now its largest funder.

• A key internal fracture: Stop AI was formed by people pushed out of Pause AI over disagreements about tactics—especially around civil disobedience and breaking the law.

• Stop AI’s activism has included serving a subpoena to Sam Altman mid-event and staging protests directly targeting AI labs.

• One Stop AI cofounder allegedly threatened violence, disappeared after an internal conflict, and is still missing.

• Another cofounder, Guido Reichstadter, has a history of dramatic protest tactics—including a hunger strike outside Anthropic and chaining himself to infrastructure.

• Stop AI says the suspect once joined its forum and explicitly asked if advocating violence would get him banned—and stopped engaging after being told yes.