The billionaire twice extended his arm out straight as he thanked the crowd for “making it happen.”

Critics, including some historians, said it was a Nazi salute – Mr Musk has dismissed that, saying comparisons with Hitler were “tired” and “dirty tricks.”

However many Reddit users have been unpersuaded by his response describing his actions as “hateful”, leading the moderators of scores of communities – or subreddits – to stop content being shared on X.

Reddit relies heavily on community moderation, where unpaid individuals known as Redditors decide what is – and isn’t – allowed to be published on their own corner of the website.

They moderate subreddits, the name given to a forum within the Reddit platform which is effectively a community of people who gather to discuss a particular interest.

Since the controversy erupted, dozens of those subreddits have decided they won’t link to content on X, potentially reducing traffic and engagement.

The biggest subreddits to have enforced the ban include basketball community r/NBA, which has 15 million members, female-focused community r/TwoXChromosomes, which has 14 million members, and American football community r/NFL, which has 12 million members.

It is worth remembering that subreddits are almost always run by fans – it does not mean that the NFL or NBA organisations are taking a stance against Musk.

The BBC has independently verified that at least 100 subreddits have banned X posts.

Of this number, more than 60 have at least 100,000 members.

But the actual number that have instituted the ban will likely be significantly higher by taking into account smaller subreddits with only a few thousand members.

And there are many more communities discussing a potential blacklisting.

The subreddits run by fans of football clubs Liverpool, Celtic and Tottenham Hotspur have all instituted the bans, as have communities for many US sports sides as well as Formula 1.

The subreddits where residents of many cities and countries gather around the world – ranging from New Jersey to South Korea – have also blocked posts to X.

And gamers are also amongst those to bring in the ban for video games including Baldur’s Gate 3 and World of Warcraft.

But while the blacklisting may have first started in some of these communities, it is popping up in a variety of places now where people gather to discuss all sorts of topics, ranging from RuPaul’s Drag Race to Disneyland and even the military.

While the vast majority of subreddits discussing a ban are in favour of it, there are some that have refused.

The moderators of the Maine community for example say they won’t institute a ban so long as “the state maintain official accounts there”.

And those running a group for people in British Columbia said they simply aren’t “doing censorship here”.

Though there are many subreddits which already disallow posts from social media, those built around professional sports in particular may have a big impact on referrals to X.

That’s because sports subreddits generally get a lot of content from links to athletes, analysts and journalists who spend a lot of time posting online.

For example, the top two most popular posts of all time on the NBA subreddits are screenshots taken from X, while three of the top ten most popular posts of all time on the AEW wrestling subreddit are screenshots from the platform.

And gaming subreddits have a similar story, with the top posts on the Animal Crossing and Kingdom Hearts communities both screenshots from X.

But that is not to say the bans will necessarily be permanent – Reddit is known for this sort of community movement to protest against wider issues, which doesn’t always work out.

In 2023, thousands of communities “went dark” to contest changes to how the platform was being run.

Some of the biggest Reddit communities then began only allowing photos and videos of comedian John Oliver, following comments from disgruntled users.

But this proved to be short-lived.

Eventually the communities mostly became publicly available again, and Reddit’s plan ultimately proved financially beneficial – the platform subsequently successfully listed on the New York Stock Exchange.

In his inaugural speech on Monday, Trump, 78, took an aggressive posture, using his podium in the Capitol Rotunda to blast his predecessor, outgoing Democratic President Joe Biden.

He also framed himself as a victim of government “weaponisation”, taking jabs at what he called a “radical and corrupt establishment”.

“My recent election is a mandate to completely and totally reverse a horrible betrayal,” Trump said. “From this moment on, America’s decline is over.”

This was Trump’s second presidency, after serving in the White House from 2017 to 2021.

But the Trump who returned to the presidency on Monday was a Trump who appeared more confident than in his first term, as he announced his intention to sign a stream of executive actions from his first moments in office.

“ With these actions, we will begin the complete restoration of America and the revolution of common sense. It’s all about common sense,” he said, citing a new pro-business energy policy and a crackdown on irregular migration as two of his first actions.

He also pledged to “expand” US borders, warning Panama that he would “take back” the canal the US built there.

Still, while Trump once again painted a portrait of the US as a country on the precipice, he tried to strike a more upbeat posture than in his 2017 inaugural address, which became known as the “American carnage” speech.

“I return to the presidency confident and optimistic that we are at the start of a thrilling new era of national success,” Trump said. “A tide of change is sweeping the country. Sunlight is pouring over the entire world. And America has the chance to seize this opportunity like never before.”

At noon Eastern time (17:00 GMT), Biden and three other former US presidents — Bill Clinton, George W Bush and Barack Obama — piled into the Capitol Rotunda with other dignitaries to witness Trump take his second oath of office.

In opening remarks, Senator Amy Klobuchar reminded the audience that the theme of Monday’s inauguration was “our enduring democracy”.

But  when Trump took the podium to deliver his inaugural address, he quickly cast a portrait of the outgoing administration as “corrupt”, without naming Biden outright.

“Our sovereignty will be reclaimed. Our safety will be restored. The scales of justice will be rebalanced. The vicious, violent and unfair weaponisation of the Justice Department and our government will end,” Trump said in the opening minutes of his speech.

While out of the White House from 2021 to 2025, Trump became the first US president to be charged and convicted of felony crimes.

His conviction came in May, after a jury found him guilty of 34 counts of falsifying business documents, related to efforts to conceal hush-money payment to an adult film star during the 2016 election.

But Trump faced three other criminal indictments in addition. They included a state case in Georgia, where prosecutors accused him of participating in a criminal conspiracy to undermine the state’s 2020 election results.

And until recently, Trump faced two federal indictments — one for allegedly seeking to overturn the 2020 election, and the other for withholding classified documents while out of office. Both cases were dropped in November, in accordance with Justice Department policy not to prosecute sitting presidents.

Trump has long denied wrongdoing in all the cases against him, and he has accused Democrats of using the Justice Department for personal “witch hunts”.

In Monday’s speech, he tied the criminal probes to an assassination attempt he faced in July, while campaigning in Butler, Pennsylvania.

“Over the past eight years, I have been tested and challenged more than any president in our 250-year history,” Trump said.

“The journey to reclaim our republic has not been an easy one — that, I can tell you. Those who wish to stop our cause have tried to take my freedom and, indeed, to take my life.”

Trump’s inaugural speech also sought to make good on promises the Republican delivered on the campaign trail.

His first priority, he said, was to declare an emergency on the southern border with Mexico.

“All illegal entry will immediately be halted. And we will begin the process of returning millions and millions of criminal aliens back to the places from which they came,” Trump said.

As part of that push, Trump explained he would send troops to the border “to repel the disastrous invasion of our country”.

He also pledged to reimplement his 2019 “Remain in Mexico” policy, which required asylum seekers to stay on the other side of the border while waiting for their immigration appointments and court dates.

Critics, however, had challenged the policy as a violation of domestic and international asylum law, pointing out that asylum seekers have the right to cross international borders to flee imminent persecution. They also argued that parts of the Mexican border were unsafe for migrants and asylum seekers to remain in, due to the presence of criminal activity.

Biden  attempted to end the policy in February 2021, shortly after taking office, and it has since been wrapped up in litigation.

Also in Monday’s speech, Trump repeated his false assertion that foreign countries were emptying their prisons and mental health institutions across the US border, and he pledged to designate drug-trafficking cartels as “foreign terrorist organisations”.

Then, he added, he would invoke the  Alien Enemies Act of 1798, which allows the president to detain and deport foreign nationals during times of war, to go after “all foreign gangs and criminal networks”.

“As commander in chief, I have no higher responsibility than to defend our country from threats and invasions, and that is exactly what I am going to do,” Trump said.

An estimated 11 million people live in the US without legal authorisation, and human rights advocates fear Trump’s proposed crackdown may extend beyond criminal networks, ultimately fissuring families and communities.

Trump  painted a rosy picture of life under his incoming presidency: one in which the US is prosperous and growing.

But in doing so, he used loaded language like “manifest destiny”, a term associated with the westward expansion of colonialism across North America, forcibly displacing Indigenous peoples.

“ The United States will once again consider itself a growing nation, one that increases our wealth, expands our territory, builds our cities, raises our expectations and carries our flag into new and beautiful horizons,” he said.

“And  we will pursue our manifest destiny into the stars, launching American astronauts to plant the Stars and Stripes on the planet Mars.”

In the lead-up to his inauguration, Trump has made repeated references to expanding US territory abroad.

In Central America, he has urged Panama to “return” the Panama Canal, claiming unfair trade practices across the US-built waterway. To the north, he has encouraged Canada to become the US’s “51st state”. And in the case of Greenland, he has refused to rule out “military or economic coercion” in his push to assimilate the autonomous Danish territory.

Trump reprised several of those issues in his inauguration speech, accusing Panama of treating the US “very badly”.

“We gave it to Panama,” Trump said of the canal. “And we’re taking it back.”

Trump also called for the Gulf of Mexico to be renamed the “Gulf of America”, and he said he would revert the name of an Alaskan mountain, currently known by its Indigenous name Denali, to “Mount McKinley”.

In his speech, Trump depicted the US’s colonial era as a time of triumph, arguing that present-day Americans need to return to the spirit of that age.

“The spirit of the frontier is written into our hearts. The call of the next great adventure resounds from within our souls,” Trump said.

“Our American ancestors turned a small group of colonies on the edge of a vast continent into a mighty republic of the most extraordinary citizens on earth. No one comes close.”

 part of his depiction of an America in crisis, Trump sketched a vision of the US hampered by censorship, a recurring theme in the conservative sphere in recent years.

“After  years and years of illegal and unconstitutional federal efforts to restrict free expression, I will also sign an executive order to immediately stop all government censorship and bring back free speech to America,” Trump said.

But he pivoted from there to attacking efforts to educate about racism and enduring racial divides, through diversity initiatives in schools and businesses. Many conservatives have deemed such programmes “woke” and have called for them to be dismantled.

He also made allusions to his campaign promises to dismantle protections for transgender and nonbinary Americans.

“ I will also end the government policy of trying to socially engineer race and gender into every aspect of public and private life. We will forge a society that is colour-blind and merit-based,” he said.

“As of today, it will henceforth be the official policy of the United States government that there are only two genders: male and female.”

Despite the divisive rhetoric, Trump repeatedly described himself as a “unifier” in his speech, ushering in a new age of prosperity.

“My proudest legacy will be that of a peacemaker and unifier. That’s what I want to be: a peacemaker and a unifier,” he said. That spirit will extend beyond the US’s borders, he added.

“ We will be a nation like no other full of compassion, courage and exceptionalism. Our power will stop all wars and bring a new spirit of unity to a world that has been angry, violent, and totally unpredictable.”

Speaking from Capitol Hill, Al Jazeera correspondent Alan Fisher called the speech a “very dark” one.

“This  was Donald Trump effectively settling scores,” Fisher said, comparing it to a campaign speech.

Fisher described Biden and Vice President Kamala Harris, Trump’s rival in the 2024 race, as sitting “stony-faced” in the audience, only rising to their feet when the release of Israeli captives in Gaza was mentioned.

Addressing Trump supporters hours after the Republican was inaugurated as the 47th US president on Monday, Musk hailed the outcome of the US presidential election on November 4 as “no ordinary victory”.

“This was a fork in the road of human civilization,” Musk said at the Capital One Arena in Washington, DC.

“This one really mattered. Thank you for making it happen! Thank you.”

Musk then thumped his right hand into his chest before extending his arm in an upward angle with his palm down and fingers together.

The Tesla and SpaceX CEO, who has been tasked with leading the so-called Department of Government Efficiency in Trump’s administration, then turned around to face the crowd behind him and repeated the gesture.

Musk’s  actions drew immediate scrutiny online, with some social media users accusing him of giving the infamous Sieg Heil salute associated with Adolf Hitler.

“This  honestly could not look more like a Nazi salute,” British journalist and commentator Owen Jones said in a post on X.

The gesture also drew scrutiny in Israeli media, with the newspaper Haaretz saying Musk appeared to conclude his remarks with a “‘Roman salute,’ a fascist salute most commonly associated with Nazi Germany”.

‘Not a Nazi salute’

Others defended Musk, including The Anti-Defamation League (ADL), one of the most prominent organisations dedicated to opposing anti-Semitism, which said the billionaire had made an “awkward gesture in a moment of enthusiasm, not a Nazi salute”.

“In this moment, all sides should give one another a bit of grace, perhaps even the benefit of the doubt, and take a breath,” the ADL said in a post on X.

“This is a new beginning. Let’s hope for healing and work toward unity in the months and years ahead.”

Al Jazeera did not immediately receive a response to requests for comment sent to Musk’s lawyer and a number of his companies.

Musk’s politics have shifted sharply right since he publicly came out in support of Trump after the Republican narrowly survived an attempted assassination in July.

Earlier this month, the billionaire hosted Alice Weidel, the leader of Germany’s far-right Alternative for Germany, for a conversation on his social media platform X after endorsing her party in February’s national elections.