Elon Musk has ignited controversy after performing two back-to-back gestures at United States President Donald Trump's inauguration, leading to him being accused of making a Nazi salute.
Mr Musk made the gestures during an event in Washington DC celebrating Mr Trump's inauguration on Monday evening, local time.
"This was no ordinary victory," the Tesla CEO said to the crowd inside Capital One Arena.
"This was a fork in the road of human civilisation," he said.
"This one really mattered.
"I just want to say thank you for making it happen."
He slapped his hand to his chest and extended his arm outward and upward.
Mr Musk then turned around and made the gesture again while facing the other way.
"My heart goes out to you," he said as he finished the gesture.
Viewers and critics quickly took to social media to express outrage, while white supremacist groups vocalised support of the gesture.
Other supporters attempted to provide alternate explanations.
Mr Musk has denied it was a Nazi salute, writing on X: "The 'everyone is Hitler' attack is sooo tired."
Despite being called to, Mr Musk hasn't offered any further explanation.
Some say it was not a Nazi salute but a Roman salute, also used in the era of Italian dictator Benito Mussolini.
So what is the difference, and how has the gesture been embraced by right-wing extremists?
What is the Nazi salute?
The Nazi salute, or Hitler salute, was used in Germany in the 1930s to pay homage to fascist leader Adolf Hitler.
The gesture involves raising an outstretched arm with the palm down.
In Nazi Germany, it was usually accompanied by shouts of "Heil Hitler" or "Sieg Heil".
In January 2024, a national law was implemented in Australia making it illegal to perform the Nazi salute in public or publicly display, or trade in, Nazi hate symbols.
New South Wales, Queensland, Tasmania, Victoria and Western Australia have also banned it.
It is also illegal in Germany.
Neo-Nazis and other white supremacists have continued to use the salute since World War II.
It is not illegal in the United States.
What is the Roman salute?
Known as the Roman salute in Italy, the straight-arm greeting — officially adopted in 1925 by Mussolini's fascist regime — is banned in Italy, though it is rarely prosecuted.
Mr Musk's representative in Italy, Andrea Stroppa, published the photo on X with the words: "Roman Empire is back, starting with the Roman salute," according to the news agency ANSA.
He later deleted the post, writing that Mr Musk "is autistic," and was expressing his emotions but denying he was emulating fascism.
"He does not like extremists,'' Mr Stroppa wrote.
Both the Nazi and Roman salutes are considered hate symbols by the reporting radicalism initiative.
The Nazis claimed it was a greeting in ancient Rome, but there is no concrete evidence of that fact.
So, was it a Nazi salute?
Brian Levin, founder of the Center for the Study of Hate and Extremism at California State University, San Bernardino, said even if it was accidental, the gesture Mr Musk made has the power to hurt people.
"When you're a public figure at the highest echelons of power on Inauguration Day, doing a salute like that is extraordinarily disturbing, and it calls for an explanation from Mr Musk," he said.
"Points are made about free speech. Well, along with free speech comes responsibility."
Mr Levin said some extremists will take the gesture, regardless of its intent, as "some kind of not-so-subtle marching order".
Meanwhile, the US Anti-Defamation League urged calm at what it called a "delicate moment" in a statement on Monday.
"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.
"In this moment, all sides should give one another a bit of grace, perhaps even the benefit of the doubt, and take a breath."
Kurt Braddock, a professor of communication at American University who studies extremism, radicalisation and terrorism, said the gesture was a fascist salute and "people shouldn't doubt what they saw".
"He's still blowing it off as though it wasn't something serious," Professor Braddock said of Mr Musk.
"I know what I saw, I know what the response to it was among elements of the extreme right including neo-Nazis, and I see what the reaction is now. And none of it is a laughing matter.
"I'm sceptical it was on purpose," said Jared Holt, a senior research analyst at the Institute for Strategic Dialogue which tracks online hate, told the Associated Press.
"It would be an act of self-sabotage that wouldn't really make much sense at all."
What have far right-wing groups said?
The gesture, regardless of its intent, has been embraced by far-right extremist groups on social media.
"The White Flame will rise again," a chapter of the white nationalist group White Lives Matter posted on Telegram.
"Maybe woke really is dead," white nationalist Keith Woods posted on X.
"Did Elon Musk just Heil Hitler …" right-wing commentator Evan Kilgore posted on X.
"We are so back."
ABC/AP