Musk took the Capital One Arena stage in Washington to huge cheers, pumping his arms and shouting, "Yesssss."

"This was no ordinary victory. This was a fork in the road of human civilization," he said. "This one really mattered. Thank you for making it happen! Thank you," he said.

Biting his bottom lip, he thumped his right hand over his heart, fingers spread wide, then extended his right arm out, emphatically, at an upward angle, palm down and fingers together. Then he turned and made the same hand gesture to the crowd behind him.

"My heart goes out to you. It is thanks to you that the future of civilization is assured," he said as he finished the gesture.

The gestures were quickly scrutinized online.

"Did Elon Musk Sieg Heil at Trump's inauguration?" asked the Jerusalem Post.

The Anti-Defamation League, which tracks antisemitism disagreed. "It seems that @elonmusk made an awkward gesture in a moment of enthusiasm, not a Nazi salute, but again, we appreciate that people are on edge," it posted on Monday.

Spokespeople for Musk and Trump did not immediately reply to requests for comment.

Soon after his speech, Musk posted a Fox video clip of portions of his speech on his social media network X, that cut away from the podium when he made the first gesture while facing the cameras. "The future is so exciting," he wrote above it.

Some X users came to Musk’s defense, claiming that Musk was expressing “my heart goes out to you” and criticizing posts that suggested otherwise.

Musk has backed the far-right Alternative for Germany (AfD), an anti-immigration, anti-Islamic party labeled as right-wing-extremist by German security services, in an upcoming national election. He hosted a broadcast with the party's leader on his social media platform earlier this month.