Billionaire Elon Musk's hand gesture while he spoke during a celebration of US president Donald Trump's inauguration drew online comparisons to a Nazi salute on Monday.
However, a leading tracker of antisemitism said it appeared to represent a moment of enthusiasm instead.
Mr Musk dismissed criticism of the hand gesture as a "tired" attack.
Mr Musk took to 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 civilisation," 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 civilisation is assured," he said as he finished the gesture.
The gestures were quickly scrutinised online.
Billionaire Elon Musk sparked controversy after making a gesture at an event celebrating US President Donald Trump's inauguration, with some calling it a "Nazi" or "fascist" movement | Read more: https://t.co/jKZDWpSCtW pic.twitter.com/6fb4tbyLtA
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"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.
"Frankly, they need better dirty tricks. The 'everyone is Hitler' attack is sooo tired," Mr Musk said on his social media platform X late on Monday.

Soon after his speech, Mr Musk posted a Fox video clip of portions of his speech on 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.
A spokesperson for Mr Trump did not immediately reply to requests for comment.
Some X users came to Mr Musk's defence, claiming that Mr Musk was expressing "my heart goes out to you" and criticising posts that suggested otherwise.
Mr Musk has backed the far-right Alternative for Germany (AfD), an anti-immigration, anti-Islamic party labelled 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.