SYDNEY, Australia — He traveled abroad, visiting places where extremists once killed civilians in cold blood. He appears to have posted radical opinions online. He moved overseas, applied for gun licenses and is believed to have purchased several assault rifles.
But Brenton H. Tarrant escaped the attention of the authorities both in Australia, where he was born and spent most of his life, and New Zealand, where he relocated in recent years and is alleged to have assembled his arsenal. He now stands accused of killing 51 Muslims at two mosques in Christchurch last March.
On Friday, he pleaded not guilty to 92 counts, including murder and terrorism, and a trial has been scheduled for May. In the long months until then, Australia and New Zealand will continue to grapple with a difficult question: Could the massacre have been prevented?
Or, more pointedly: Have Australia and New Zealand neglected the threat of right-wing extremism as they have overwhelmingly focused on the peril of Islamist terrorism?
In New Zealand, the government is conducting an official inquiry that is intended in part to determine whether the country’s intelligence and security services paid insufficient attention to the threat posed by far-right extremists.
“Questions need to be answered around whether or not this was the activity of an individual we could or should have known about,” New Zealand’s prime minister, Jacinda Ardern, said in announcing the inquiry on March 25, 10 days after the attacks.
No such national investigation has been commissioned in Australia, a country that has often avoided painful debates about the sort of racism Mr. Tarrant is accused of espousing.
Current and former Australian officials said the authorities rarely focused on right-wing extremists, partly because security officials are less likely to see groups that are mostly white as a threat, partly because of limited resources, and partly because the paranoia and distrust of government among those groups make them hard to infiltrate.
After the terrorist attacks of Sept. 11, 2001, security agencies in Australia and New Zealand, like their counterparts in the United States, shifted their focus to the urgent threat of radical Islamism. In the years before 9/11, the focus in Australia was on crimes like the smuggling of drugs and people.
Over the nearly 18 years since, the threat from Islamist extremism has persisted, with the Islamic State showing that it can carry out or inspire deadly attacks across the globe. In 2014, for instance, a Muslim man held 18 people hostage in a cafe in Sydney’s central business district, and two died in an ensuing police operation. The man had pledged allegiance to ISIS.
Nicholas J. Rasmussen, who led the American government’s National Counterterrorism Center from 2014 to 2017, said that given the focus on radical Islamism, United States intelligence services could do more to investigate right-wing extremism online and share that information with American allies.
“I think in my time when I was in government and had counterparts in the U.K. and Australia, ‘Five Eyes’ partners, very close professional and personal relationships, not once did this topic come up, which is kind of crazy when you think about it,” Mr. Rasmussen said in an interview. He was referring to the so-called Five Eyes — the United States, Britain, Canada, Australia and New Zealand — which broadly share intelligence.
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Australian crime data reflects the intense focus on Islamist extremism. The federal police said that of 15 terrorist operations disrupted since September 2014, only one was related to right-wing extremism.
While experts say the threat from white supremacism in Australia is most likely greater than those figures indicate, it is difficult to know just how big it is. Australia, unlike the United States, Canada and other Western countries, does not track hate crimes.
Tim Soutphommasane, who was the race discrimination commissioner for Australia from 2013 to 2018, said he had repeatedly pushed for the creation of a database to record reports of hate crimes. The absence of data has made it difficult to track trends, he added.
“I also made clear last year when I was still in the commission role that I believed that the state of race relations had deteriorated, and that political debates were at risk of normalizing racism,” Mr. Soutphommasane said in an interview.
“As commissioner, it was my unequivocal view,” he added, “based on what various communities were conveying to me, that many people felt that the danger posed by racist extremism was more pronounced than it had been in the past.”
New Zealand also did not track hate crimes before the Christchurch attacks, but the government has called current laws on hate speech inadequate and is looking at ways to strengthen them.
Two weeks after the massacre, the country’s spy agencies were authorized to increase their “intrusive” activities and put more people under surveillance.
Andrew Little, the government minister in charge of the intelligence agencies, said in an interview that the country’s primary spy agency, the Security Intelligence Service, had started to examine the threat of far-right extremism to New Zealand in the middle of last year.
The examination was prompted, he said, by the white nationalist rallies in Charlottesville, Va. — which had taken place a year earlier — as well as “events happening in Europe.”
“They were doing what they call a baseline review, so that was really taking the time to gauge what was happening,” Mr. Little said.
He said he was unsure whether the work had gotten as far as identifying specific white supremacists or groups in New Zealand, and he would not say whether he had signed any warrants allowing individuals linked to far-right groups to be spied on.
“I don’t know how far they’d got,” Mr. Little said.
In an annual public report recounting its activities, the spy agency referred several times to the threat from Islamist terrorism and the Islamic State, but the agency’s new activity on far-right extremism garnered no mention.
In fact, there have been no references to white supremacism or far-right extremism in any of the agency’s annual reports since the 2001 attacks. Even segments devoted to emerging threats, or to the risk of New Zealanders being radicalized online, have been silent about the far right.
Asked if he had confidence in New Zealand’s intelligence apparatus, Mr. Little said that “until there’s a very microscopic look at what the agencies have been doing, and whether they’ve missed anything, I can’t say for certain.”
As New Zealand vowed action in the days after the Christchurch attacks, Australia’s Parliament issued condolences and increased the security budget to provide added protections at places of worship. It then passed a law that threatens huge fines to social media companies and jail for their executives if they fail to remove “abhorrent violent material” quickly from their sites.
But there has been no movement toward bolstering hate crime laws or creating a database to track such crimes.
In the United States, the threat from right-wing extremists has also been somewhat obscured. In the decade and a half after the Sept. 11 attacks, nearly twice as many people were killed by white supremacists, antigovernment fanatics and other non-Muslim extremists than by radical Islamists. But efforts by the F.B.I. to investigate and prosecute right-wing extremists have been made more difficult because of First Amendment concerns.
Before the Christchurch attacks, New Zealand — long seen as a particularly safe and peaceful nation — had struggled to imagine where any terrorism threat would come from other than from Islamist extremism. One spy agency’s annual report from the mid-2000s noted that citizens were more likely to be caught up in peril overseas than to face any threat of terrorism within New Zealand’s borders.
But as hate speech courses through the global internet, and is even amplified by the algorithms of platforms like YouTube, borders do little to contain the threat.
Mr. Tarrant is believed to have posted extremist views on anonymous online forums like 8chan. He is alleged to have connected online with a spokesman for Austria’s far-right youth movement. Shortly before the attacks, he apparently published on 8chan a link to a 74-page manifesto — a stew of white nationalist and fascist rhetoric. And the massacre itself was live-streamed there. On Tuesday, a white supremacist in Christchurch was sentenced to 21 months in jail for distributing the video.
“I think Christchurch opened our eyes, where previously we weren’t aware of the global nature of the connections” among extremists who in the past might have been seen as lone wolves, said Lydia Khalil, who worked as a counterterrorism adviser to the Boston and the New York Police Departments.