The murderous assault Friday on two mosques in New Zealand — committed by a shooter whose weapon bore neo-Nazi symbols and the names of right-wing extremists — could be viewed as the act of an individual pursuing his own racist fantasies.

But extremism experts say such attacks are better understood as springing from a global network of white supremacy cells that communicate in much the same way as other global terrorist networks.

The Christchurch massacre “underscores that violent white supremacists are an international threat,” said Oren Segal, director of the Anti-Defamation League’s Center on Extremism.

“We tend to focus on international threats like al-Qaeda and ISIS, but when you look at the way that white supremacist ideas impact people, are spread, et cetera, there’s really little difference,” Segal said.

The rampage in New Zealand that took 49 lives appears to be the latest attack during the past decade globally by white supremacists.

In 2011, a white supremacist and neo-Nazi murdered 77 people in Norway. In 2015, a white supremacist walked into a Charleston, S.C., church with a gun and killed nine people. In 2017, a white supremacist shooter killed six and injured 19 at a mosque in Canada. In 2018, a neo-Nazi and failed political candidate in Italy targeted and shot immigrants, injuring six.

In each instance, the shooters acted alone but were clearly influenced by social media and engaged with other white supremacists or their ideology online.

It’s essential to understand the fibers that connect these individuals, said Kathleen Belew, author of “Bring the War Home: The White Power Movement and Paramilitary America” and an assistant professor of history at the University of Chicago.

White supremacist violence has surged in recent years in the United States. During the past decade, attackers motivated by right-wing political ideology are responsible for more acts of violence than any other category of domestic extremist, according to a 2018 Washington Post analysis of data on global terrorism.

“It very difficult to put together a public understanding of white power as a movement rather than as a series of one-off events that have nothing to do with each other,” Belew said. “But they’re all motivated by the same ideology, the same websites, the same broad understanding of the world.

“It really is a social movement and the common frame is really apparent.”

Before embarking on the deadly shooting rampage Friday in New Zealand, the suspected gunman — a 28-year-old, self-styled “regular white man from a regular family” — posted a 74-page manifesto on Twitter. In it, he referenced numerous international figures; claimed he had made brief contact with Anders Breivik, the Norwegian white supremacist who murdered 77 people in 2011; and expressed admiration for President Trump “as a symbol of renewed white identity and common purpose.”

Some experts cautioned against taking the manifesto at face value, noting that the suspected attacker knew it would get media coverage.

“Keep in mind this person knew he would get a tremendous amount of attention for this attack and is trying to control the message,” said Adam Lankford, a criminology professor at the University of Alabama and an expert in mass shootings.

The sprawling, angry text may shed some light on the motivation behind an attack that killed 49 people during Friday prayers and wounded dozens of others. Among other things, the suspect — who Christchurch police say posted the manifesto and whom they have since charged with murder — wrote that a trip to France in 2017 convinced him that the country was under “invasion” by “nonwhites.”

“The final push was witnessing the state of French cities and towns. For many years I had been hearing and reading of the invasion of France by nonwhites, many of these rumors and stories I believed to be exaggerations, created to push a political narrative,” the suspect wrote.

“But once I arrived in France, I found the stories not only to be true, but profoundly understated,” he continued. A significant detail is that the suspect titled his manifesto “The Great Replacement,” a clear reference to the title of a 2012 book by right-wing French polemicist Renaud Camus.

In that book, Camus expounds on the “theory” that Europe’s white majority is being replaced by North African and sub-Saharan African immigrants, many of whom are Muslim.

The “great replacement” has been a battle cry of the French far right, even after immigration arrivals into Europe fell significantly after their peak in 2015. In the words of Marion Maréchal, granddaughter of convicted Holocaust denier Jean-Marie Le Pen and a favorite of the American far right, the idea perfectly corresponds to reality.

“Today, there is in fact a substitution of certain parts of the territory of so-called native French by a newly immigrated population,” she said in 2015.

The notion of “massive immigration” that will inevitably provoke a violent cultural clash has spread from the fringes of French public discourse into the political mainstream. Laurent Wauquiez, leader of France’s mainstream conservative party, Les Républicains, likewise called Camus’s idea “a reality” in 2017.

It has also crossed oceans. In Charlottesville, in August 2017, protesters chanted “Jews will not replace us!” (In 2018, Camus released another book, this time titled “You Will Not Replace US!”)

In Pittsburgh last October, the shooter who killed 11 Jews in the deadliest anti-Semitic attack in U.S. history was apparently motivated by outrage over immigration, and specifically the activities of HIAS, originally the Hebrew Immigrant Aid Society, which provides humanitarian assistance to refugees.

For Farhana Khera, president and executive director of Muslim Advocates, the anger over immigration and the reference to Trump in the shooter’s manifesto is a troubling confirmation of concerns that many in the U.S. Muslim community have about the climate created by the president’s rhetoric.

“Trump is not going out and carrying out these attacks, but he has had a drumbeat of demonizing Muslims and immigrants, saying that we should be feared and that we’re violent and that we don’t belong,” Khera said. “In this administration we have not seen any indication that there is any kind of attention to the threat that’s being posed by white nationalists. If anything, what’s particularly disturbing is that the white nationalist threat has only gotten more brazen and more deadly.”

On Friday, Trump said he did not think that white nationalists were a growing threat around the world. “I think it’s a small group of people that have very, very serious problems,” he told reporters at the White House. “It’s certainly a terrible thing.”

Reached by phone Friday morning at his home in southwestern France, Camus, now 72, told The Washington Post that he condemns the Christchurch attacks and has always condemned similar violence. But when asked whether he objects to how his “great replacement” idea has been interpreted by the general public, including far-right politicians and their supporters, he said he does not.

“To the fact that people take notice of the ethnic substitution that is in progress in my country?” he asked. “No. To the contrary.”

Camus added that he still hopes that the desire for a “counterrevolt” against “colonization in Europe today” will grow, a reference to increases in nonwhite populations.

“I hope it becomes stronger,” he said, claiming that this apparent “demographic colonization” was “20 times more important than the colonization Europe did to Africa, for example.”

French Muslims, meanwhile, lament the extent to which these views are tolerated in polite society in France.

“On the one hand, Renaud Camus is portrayed as an extremist ideologue for the far right, but he’s also being invited on France Culture,” said Yasser Louati, a Muslim community organizer in Paris. “He’s given a platform.”

France Culture is among the most highbrow radio programs in Europe, a French equivalent of NPR. Camus has also discussed the “great replacement” on “Répliques,” a program anchored by Alain Finkielkraut, a prominent French intellectual.

“I’m just upset that we keep pretending all of this is a surprise,” Louati said, “when in fact it’s become normalized.”

Joe Heim reported from Washington, and James McAuley reported from Paris.

Mark Berman and Katie Zezima contributed to this report.