The revelations about Mr. Breivik’s American influences exploded on the blogs over the weekend, putting Mr. Spencer and other self-described “counterjihad” activists on the defensive, as their critics suggested that their portrayal of Islam as a threat to the West indirectly fostered the crimes in Norway. 
 
 Mr. Spencer wrote on his Web site, jihadwatch.org , that “the blame game” had begun, “as if killing a lot of children aids the defense against the global jihad and Islamic supremacism, or has anything remotely to do with anything we have ever advocated.” He did not mention Mr. Breivik’s voluminous quotations from his writings. 
 
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 The Gates of Vienna, a blog that ordinarily keeps up a drumbeat of anti-Islamist news and commentary, closed its pages to comments Sunday “due to the unusual situation in which it has recently found itself.” 
 
 Its operator, who describes himself as a Virginia consultant and uses the pseudonym “Baron Bodissey,” wrote on the site Sunday that “at no time has any part of the Counterjihad advocated violence.” 
 
 The name of that Web site — a reference to the siege of Vienna in 1683 by Muslim fighters who, the blog says in its headnote, “seemed poised to overrun Christian Europe ” — was echoed in the title Mr. Breivik chose for his manifesto: “2083: A European Declaration of Independence.” He chose that year, the 400th anniversary of the siege, as the target for the triumph of Christian forces in the European civil war he called for to drive out Islamic influence. 
 
 Marc Sageman, a former C.I.A. officer and a consultant on terrorism, said it would be unfair to attribute Mr. Breivik’s violence to the writers who helped shape his world view. But at the same time, he said the counterjihad writers do argue that the fundamentalist Salafi branch of Islam “is the infrastructure from which Al Qaeda emerged. Well, they and their writings are the infrastructure from which Breivik emerged.” 
 
 “This rhetoric,” he added, “is not cost-free.” 
 
 Dr. Sageman, who is also a forensic psychiatrist, said he saw no overt signs of mental illness in Mr. Breivik’s writings. He said Mr. Breivik bears some resemblance to Ted Kaczynski, the Unabomber, who also spent years on a manifesto and carried out his mail bombings in part to gain attention for his theories. One obvious difference, Dr. Sageman said, is that Mr. Kaczynski was a loner who spent years in a rustic Montana cabin, while Mr. Breivik appears to have been quite social. 
 
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 Mr. Breivik’s declaration did not name Mr. Kaczynski or acknowledge the numerous passages copied from the Unabomber’s 1995 manifesto, in which the Norwegian substituted “multiculturalists” or “cultural Marxists” for Mr. Kaczynski’s “leftists” and made other small wording changes. 
 
 By contrast, he quoted the American and European counterjihad writers by name, notably Mr. Spencer, author of 10 books, including “Islam Unveiled” and “The Truth About Muhammad.” 
 
 Mr. Breivik frequently cited another blog, Atlas Shrugs, and recommended the Gates of Vienna among Web sites. Pamela Geller, an outspoken critic of Islam who runs Atlas Shrugs, wrote on her blog Sunday that any assertion that she or other antijihad writers bore any responsibility for Mr. Breivik’s actions was “ridiculous.” 
 
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 “If anyone incited him to violence, it was Islamic supremacists,” she wrote. 
 
 Mr. Breivik also quoted European blogs and writers with similar themes, notably a Norwegian blogger who writes under the name “Fjordman.” Immigration from Muslim countries to Scandinavia and the rest of Europe has set off a deep political debate across the continent and strengthened a number of right-wing anti-immigrant parties. 
 
 In the United States, the shootings resonated with years of debate at home over the proper focus of counterterrorism. 
 
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 Despite the Norway killings, Representative Peter T. King , the New York Republican who is chairman of the House Homeland Security Committee, said he had no plans to broaden contentious hearings about the radicalization of Muslim Americans and would hold the third one as planned on Wednesday. He said his committee focused on terrorist threats with foreign ties and suggested that the Judiciary Committee might be more appropriate for looking at non-Muslim threats. 
 
 In 2009, when the Department of Homeland Security produced a report, “Rightwing Extremism,” suggesting that the recession and the election of an African-American president might increase the threat from white supremacists, conservatives in Congress strongly objected. Janet Napolitano , the homeland security secretary, quickly withdrew the report and apologized for what she said were its flaws. 
 
 Daryl Johnson, the Department of Homeland Security analyst who was the primary author of the report, said in an interview that after he left the department in 2010, the number of analysts assigned to non-Islamic militancy of all kinds was reduced to two from six. Mr. Johnson, who now runs a private research firm on the domestic terrorist threat, DTAnalytics, said about 30 analysts worked on Islamic radicalism when he was there. 
 
 The killings in Norway “could easily happen here,” he said. The Hutaree , an extremist Christian militia in Michigan accused last year of plotting to kill police officers and planting bombs at their funerals, had an arsenal of weapons larger than all the Muslim plotters charged in the United States since the Sept. 11 attacks combined, he said. 
 
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 Homeland Security officials disputed Mr. Johnson’s claim about staffing, saying they pay close attention to all threats, regardless of ideology. And the F.B.I. infiltrated the Hutaree, making arrests before any attack could take place. 
 
 John D. Cohen, principal deputy counterterrorism coordinator at the Department of Homeland Security, said Ms. Napolitano, who visited Oklahoma City last year for the 15th anniversary of the bombing there, had often spoken of the need to assess the risk of violence without regard to politics or religion. 
 
 “What happened in Norway,” Mr. Cohen said, “is a dramatic reminder that in trying to prevent attacks, we cannot focus on a single ideology.” ||||| Photo 
 
 — The Norwegian man charged Saturday with a pair of attacks in Oslo that killed at least 92 people left behind a detailed manifesto outlining his preparations and calling for a Christian war to defend Europe against the threat of Muslim domination, according to Norwegian and American officials familiar with the investigation. 
 
 As stunned Norwegians grappled with the deadliest attack in the country since World War II, a portrait began to emerge of the suspect, Anders Behring Breivik , 32. The police identified him as a right-wing fundamentalist Christian, while acquaintances described him as a gun-loving Norwegian obsessed with what he saw as the threats of multiculturalism and Muslim immigration . 
 
 “We are not sure whether he was alone or had help,” a police official, Roger Andresen, said at a televised news conference. “What we know is that he is right wing and a Christian fundamentalist.” 
 
 In the 1,500-page manifesto, posted on the Web hours before the attacks, Mr. Breivik recorded a day-by-day diary of months of planning for the attacks, and claimed to be part of a small group that intended to “seize political and military control of Western European countries and implement a cultural conservative political agenda.” 
 
 He predicted a conflagration that would kill or injure more than a million people, adding, “The time for dialogue is over. We gave peace a chance. The time for armed resistance has come.” 
 
 The manifesto was signed Andrew Berwick, an Anglicized version of his name. A former American government official briefed on the case said investigators believed the manifesto was Mr. Breivik’s work. 
 
 The manifesto, entitled “2083: A European Declaration of Independence,” equates liberalism and multiculturalism with “cultural Marxism,” which the document says is destroying European Christian civilization. 
 
 The document also describes a secret meeting in London in April 2002 to reconstitute the Knights Templar, a Crusader military order. It says the meeting was attended by nine representatives of eight European countries, evidently including Mr. Breivik, with an additional three members unable to attend, including a “European-American.” 
 
 The document does not name the attendees or say whether they were aware of Mr. Breivik’s planned attacks, though investigators presumably will now try to determine if the people exist and what their connection is to Mr. Breivik. 
 
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 Thomas Hegghammer, a terrorism specialist at the Norwegian Defense Research Establishment, said the manifesto bears an eerie resemblance to those of Osama bin Laden and other Al Qaeda leaders, though from a Christian rather than a Muslim point of view. Like Mr. Breivik’s manuscript, the major Qaeda declarations have detailed accounts of the Crusades, a pronounced sense of historical grievance and calls for apocalyptic warfare to defeat the religious and cultural enemy. 
 
 “It seems to be an attempt to mirror Al Qaeda, exactly in reverse,” Mr. Hegghammer said. 
 
 Mr. Breivik was also believed to have posted a video on Friday summarizing his arguments. In its closing moments, the video depicts Mr. Breivik in military uniform, holding assault weapons. Rarely has a mass murder suspect left so detailed an account of his activities. The manifesto describes in detail his purchase of chemicals, his sometimes ham-handed experiments making explosives and his first successful test detonation of a bomb in a remote location on June 13. 
 
 He intersperses the account of bomb-making with details of his television-watching, including the Eurovision music contest and the American police drama “The Shield.” 
 
 The manifesto ends with a chilling signoff: “I believe this will be my last entry. It is now Fri July 22nd, 12.51.” 
 
 Indeed, the operation appeared to have been extremely well planned. 
 
 According to the police, Mr. Breivik first drew security services to central Oslo when he exploded a car bomb outside a 17-story government office building, killing at least seven people. 
 
 Then he took a public ferry to Utoya Island, where he carried out a remarkably meticulous attack on Norway ’s current and future political elite. Dressed as a police officer, he announced that he had come to check on the security of the young people who were attending a political summer camp there, many of them the children of members of the governing Labor Party . 
 
 He gathered the campers together and for some 90 hellish minutes he coolly and methodically shot them, hunting down those who fled. At least 85 people, some as young as 16, were killed. 
 
 The police said Saturday evening that they expected the death toll to climb. There were still bodies in the bombed government buildings in Oslo, and at least four people missing on Utoya. 
 
 The police also said that unexploded munitions were still in some downtown Oslo buildings, and they had not ruled out the possibility that Mr. Breivik had accomplices. 
 
 He was equipped, the police said, with an automatic rifle and a handgun; when the police finally got to the island — about 40 minutes after they were called, the police said — Mr. Breivik surrendered. 
 
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 The police also said he had registered a farm in Rena, in eastern Norway, which allowed him to order a large quantity of ammonium nitrate fertilizer, an ingredient that can be used to make explosives. The authorities were investigating whether the chemical had been used in the bombing. 
 
 Besides the manifesto, Mr. Breivik left other hints of his motives. 
 
 A Facebook page and Twitter account were set up under his name days before the rampage. The Facebook page cites philosophers like Machiavelli, Kant and John Stuart Mill. 
 
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 His lone Twitter post, while not calling for violence, paraphrased Mill — “One person with a belief is equal to the force of 100,000 who have only interests” — suggesting what he saw as his ability to act. 
 
 Those postings, along with what was previously known about Mr. Breivik publicly, aligned with but hardly predicted the bloody rampage he would undertake on Friday. 
 
 Before then, he had been a member of the right-wing Progress Party, which began as an antitax protest and has been stridently anti-immigrant and anti-Muslim. 
 
 Joran Kallmyr, a member of the party who is now Oslo’s vice mayor for transportation, said he met Mr. Breivik several times in 2002 and 2003 at local party meetings. “He was very quiet, almost a little bit shy,” Mr. Kallmyr said. “But he was a normal person with good behavior. He never shared any extreme thoughts or speech with us. There was absolutely no reason to expect that he could do something like this. We’re very shocked.” 
 
 Mr. Breivik quit the party in 2006, apparently disappointed by the party’s move toward the center. 
 
 “He didn’t like our politics, I guess, and moved on,” Mr. Kallmyr said. 
 
 His Internet posts also indicated contempt for the Conservative Party, which he accused of having given up the battle against multiculturalism. 
 
 But on Friday he directed his firepower at the center-left Labor Party, which leads the coalition government. 
 
 “Breivik feels that multiculturalism is destroying the society and that the enforcing authority is the prime minister and the Labor Party, the lead party of contemporary Norwegian politics,” said Anders Romarheim, a fellow at the Norwegian Institute for Defense Studies. 
 
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 But the attacks, along with what appear to have been years of preparation for them, raised questions about whether the Norwegian security authorities, concentrating on threats of Islamic terrorism, had overlooked the threat from the anti-Islamic right. 
 
 “This is the Norwegian equivalent to Timothy McVeigh ,” the right-wing American who bombed a federal building in Oklahoma City in 1995, said Marcus Buck, a political scientist at the University of Tromso in northern Norway. “This is right-wing domestic terrorism, and the big question is to what extent Norwegian agencies have diverted their attention from what they knew decades ago was the biggest threat” to focus instead on Islamic militants. 
 
 The unclassified versions of the last three Norwegian Police Security Service reports assessing national threats all played down any threat by right-wing and nationalist extremists. Instead, the reports emphasized the dangers posed by radical Islam, groups opposed to Norway’s military involvement in Afghanistan and Libya , and others. 
 
 The 2011 report, released early this year, concluded that “the far-right and far-left extremist communities will not represent a serious threat to Norwegian society.” 
 
 Even after the attacks, that appeared to be the official position. 
 
 “Compared to other countries I wouldn’t say we have a big problem with right-wing extremists in Norway,” Prime Minister Jens Stoltenberg told reporters at a news conference on Saturday. “But we have had some groups, we have followed them before, and our police is aware that there are some right-wing groups.” 
 
 Even if the authorities had focused on right-wing groups, it was unlikely that they would have noticed Mr. Breivik. 
 
 Kari Helene Partapuoli, director of the Norwegian Center Against Racism, said Mr. Breivik did not belong to any violent neo-Nazi groups that she was aware of, and his Internet postings, before those of last week, did not espouse violence. 
 
 “The distance between the words spoken and the acts that he carried out is gigantic, because what he did is in a different league of what the debates have to do about,” she said. 
 
 Arild Groven, secretary general of the Norwegian Shooting Association, a sports group, confirmed that Mr. Breivik had belonged to Oslo Pistolklubb, one of the 520 clubs in the association. 
 
 “We all read and watch the news about the shootings in the United States ,” Mr. Groven said. “But it doesn’t happen here.” 
 
 Mr. Romarheim said in some ways the homegrown nature of the attack made it harder for Norwegians to accept. “With 9/11 in America, people could ask, ‘Who are they?’ and could pour their rage out on someone else,” he said. “But we can’t disavow this person, he’s one of us.”
– An American right-wing extremist is cited some 64 times in the crazed manifesto written by Norwegian mass killer Anders Behring Breivik in a bid to justify his terror attack. Robert Spencer, co-founder of the Jihad Watch and Stop Islamization of America (recently hacked) blogs denied any responsibility for the attack, calling his writings a "defense of human rights." If "somebody gets from that that they should kill, well then he's nuts," he told NBC News. But some observers believe heated hate speech can trigger such actions. “When you push the demonization of populations, you often end up with violence,” warned the research director for the Southern Poverty Law Center. The manifesto also frequently cites the blog Atlas Shrugs by Muslim-basher Pamela Gellar, who insisted that if anyone incited Breivik to violence "it was Islamic supremacists." One expert called the Norwegian tragedy a "wake up call" for US security. A 2009 Department of Homeland Security report warned of a growing threat from home-grown right-wing extremists and hate groups. “We could have a similar attack here, and that’s my greatest fear,” said former federal terror analyst Daryl Johnson. It wouldn't be fair to blame the American bloggers who influenced Breivik, a former CIA analyst tells the New York Times. Still, he adds: "This rhetoric is not cost-free."