Elon Musk and OpenAI CEO Sam Altman are fighting on X about Stargate, the infrastructure project to build data centers for OpenAI in the U.S.

It’s the latest clash in a feud between the two tech billionaires that started on OpenAI’s board and is now testing Musk’s influence with the new president.

OpenAI’s CEO has stolen Musk’s thunder and it’s a lesson for every leader. Sam Altman and Elon Musk aren’t friends. They used to be colleagues back when the two were co-founders of OpenAI, and they seemingly shared the belief that artificial intelligence could be a huge net benefit for society.

The incident lasted only seconds, but it sparked what has become a global debate about how to interpret what Musk did. Then Musk started posting Nazi-themed jokes.

After facing backlash for gestures at Trump’s inauguration event and attempts to make Nazi-related puns on X, Elon Musk told supporters of Germany’s far-right AfD party there is “too much of a focus on past guilt.