Gates has been sharpening his warnings for months. In an essay published in late August titled "The turbulent AI era is here. The choices we make now are critical," he wrote that even under the best circumstances the transition to the AI era will be one of the most turbulent times in human history. In interviews since, he has called AI "the most dangerous thing that humans have ever gone near" and said it "makes nuclear weapons look like nothing."

On the technology itself, Gates identified models without safeguards as the big near-term risk, saying the danger of models where anyone can strip out protections is very high compared with models monitored to keep cyberattackers and bioterrorists from exploiting them. Over longer timeframes, he said, the control problem applies to any state-of-the-art model. He also pointed to AI's rapid recent gains, from writing code and finding cyber flaws to reasoning in biology and disrupting the job market, as reasons society needs to be ready.

It is a continuation of a warning campaign. Back in September, Gates told Reuters that governments were "way behind" on AI, that he had been talking with world leaders including President Trump about his concerns, and that he was trying to meet China's President Xi Jinping.