The man who opened fire in a Sikh temple in Wisconsin was not just a crazed loner, but a vocal neo-Nazi – in fact, his white supremacist ideology reflected a growing form of extremism that expresses its strength through violence rather than at the ballot box

On Saturday 28 July 2012, Wade Michael Page walked into the Shooters Shop in Wisconsin to buy a 9mm semi-automatic handgun, and ammunition. Eight days later, the 40-year-old military veteran arrived at a Sikh temple in Oak Creek and began shooting at members of the congregation who had gathered to prepare a meal. During the shooting, six members of the Sikh community, one police officer and the attacker were killed.

Within hours of the shootings, the Southern Poverty Law Centre (SPLC) revealed that Page was a known white supremacist. He had links to networks including the Hammerskin Nation and was involved in an underground music scene often referred to as "white power music" or "hate rock". Influenced strongly by earlier bands in England such as Skrewdriver, white power music is seen by those who study extremism as one of the most important recruitment tools for the modern far right. Page's involvement appears to have been deep: in an interview with online music magazine Label56.com in 2005, he claimed to have sold all of his possessions so that he could travel around the country attending white power festivals such as Hammerfest. The next year he formed a band called End Apathy recruiting bandmates from the other groups such as Definite Hate and 13 Knots. Asked in 2005 to elaborate on the meaning of the band's lyrics, Page replied: "The topics vary from sociological issues, religion, and how the value of human life has been degraded by being submissive to tyranny and hypocrisy that we are subjugated to."

Page's body also contained references to white supremacism. A tattoo of the number "14" was a direct reference to the so-called "14 words" that occupy a central role in neo-Nazi vocabulary: "We must secure the existence of our people and a future for white children." This passage, a reference to a section of Mein Kampf, was popularised by David Lane, a member of white supremacist terror group The Order. Another tattoo of the Odin or Celtic cross represents one of the most popular symbols among neo-Nazis, seen as the international symbol for "white pride". Those who had been close to Page confirmed his ideological affinity to the extreme right. Reflecting a wider belief within the movement, an old army friend of Page claimed that as far back as the 90s he had talked about "racial holy war", and would rant "about mostly any non-white person".

As with the aftermath of the attacks by Anders Breivik in Norway, it was not long until sympathisers surfaced online. "Take your dead and go back to India and dump their ashes in the Ganges, Sikhs," wrote one neo-Nazi. Others praised their "brother": "All I feel is loss and sympathy for a brother that was overwhelmed by pain and frustration. I could [sic] care less though for those injured and wounded other than Wade." Another warned of future attacks: "There are thousands of other angry White men like Page, the vast majority of them unknown ... When will they, like Page, reach their breaking point...?"

The threat of violence from disgruntled rightwing extremists is not lost on the security services, or analysts. In 2009, Daryl Johnson, an analyst at the Department for Homeland Security, authored a report that explicitly warned of the growing threat of far-right violence. Pointing to the economic downturn, the election of Barack Obama and evidence that some military veterans were struggling to re-integrate into civilian life, the report was one of the first to flag the growing importance of the extreme right – a movement that was routinely overlooked after 9/11. Few, however, took the warning seriously. Rather, Republicans and rightwing commentators openly criticised the report. Some saw it as an attempt to discredit the insurgent and right-wing Tea Party movement while many viewed it as an unfair attack on military veterans. Others said it focused unnecessarily on domestic rather than foreign manifestations of terrorism.

But Johnson (who was later shunted into a different department) was not wrong. Following Wisconsin, some analysts reminded commentators that the far right is responsible for as many – if not more – attacks on US soil than religious-based extremists, and now poses the most significant domestic security threat. Indeed, prior to 9/11 the most damaging act of terrorism within the US was the bombing of a federal building in Oklahoma by militia sympathiser Timothy McVeigh, which resulted in 168 deaths and more than 800 injuries. Between 1990 and 2010 the far right committed 145 ideologically motivated homicide incidents in the US. Of these incidents, excluding the bombing in Oklahoma City, far-right extremists killed 180 people.

The data suggests that American far right groups have grown "explosively", which is attributed to a potent combination of public anxieties over the financial crisis, the growth of conspiracy theories, the exploitation of fears over non-white immigration and the prospect of Obama securing a second term in office.

According to the SPLC, in 2011 the number of "hate groups" active in the US reached 1,018, 69% more than in 2000. The most striking growth has been within the "patriot" scene, which contains anti-government groups that cling to conspiracy theories and view the government as enemy number one. There were fewer than 150 of these (mostly inactive) groups in 2000. By 2011, there were almost 1,300. In fact, since 2009 this particular variant of the far right has grown at a rate of 755%.

While it is difficult to compare across borders, similar warnings have been voiced in Europe. Last year, the Federal Office for the Protection of the Constitution in Germany noted that while the number of people in far-right political parties had contracted to 22,000, the number of those involved in more combative and confrontational forms of far-right politics was on the rise: the number of rightwing extremists with a propensity to violence had increased to 9,800; the number of followers of more violence-prone neo-Nazi groups had risen to 6,000; and the number of street-based demonstrations had reached an all-time high.

Though less affected than other countries, from 2001 onward, authorities in the UK have similarly voiced concern over a rapidly evolving far-right scene. In recent years, at least 17 individuals who committed or planned acts of violence or terrorism, and who were linked to the far right, have been imprisoned. In 2009, the discovery of a network of rightwing extremists in England with access to an arsenal of weapons prompted London Metropolitan police to warn that far-right militants might attempt a "spectacular" attack. In the same year the English Defence League (EDL) was born, introducing a new form of far-right politics that is less interested than its predecessors in elections, and more focused on rallying support through street-based confrontation and networks that transcend national borders.

A candlelight vigil following the shooting at a Sikh temple in Wisconsin, Photograph: Chris Wilson/AP

Though often dismissed as alarmist, these warnings were partly validated in July 2011, when Breivik launched his politically motivated attacks in Oslo and on the island of Utøya. Shortly afterward, authorities in Germany discovered that a violent neo-Nazi cell – the National Socialist Underground (NSU) – had been responsible for at least a dozen murders. Then, in Florence, an activist connected to the far-right group Casa Pound shot dead two immigrant street traders in an unprovoked attack. While it might be tempting to treat the attack in Wisconsin in isolation, it is actually the latest in a series of acts of violence from individuals linked to far-right groups.

The perpetrators of these attacks are often dismissed as crazed and psychologically flawed loners. Perhaps this is because we have grown used to the security threat from religious extremists and tend to view their far-right counterparts as a loony fringe, rather than rational agents who are using violence to achieve certain goals. What Breivik in Norway, Gianluca Casseri in Florence, the "London nailbomber" David Copeland and Michael Page all share in common is that they arrived at violence following a longer involvement with far-right extremism. For more recent examples – such as Breivik – their attacks followed an almost total immersion in online "virtual communities". These perform a crucial role in cultivating a set of narratives that are often later used to justify violence. These include emphasis on the perceived threat of racial or cultural extinction, belief in an impending and apocalyptic conflict (a "race war" or "clash of civilisations"), belief that urgent, radical action is required and that followers have a moral obligation. In short, only by engaging in violence can they defend the wider group from various threats in society.

This preference for violence or terrorism reflects a viewpoint within the far right that has long prioritised "direct action" over a ballot-box strategy. For much of the past two decades in Europe, the strength of the far right has been measured through its number of votes at elections. But it is important to note that – for some within this scene – strength is measured as the ability and willingness to engage in violent action against "enemies" that are seen to threaten the racial purity and survival of the native group. These enemies can beimmigrants, minority groups, future leaders of mainstream parties or the state.

Identifying and tracking the Breiviks and Pages of this world will always be extremely difficult. But the reality is that – at least for the past 10 years – western democracies and their security agencies have focused almost exclusively on only one form of violent extremism. The far right may still pose less of a threat than al-Qaida-inspired groups, say, but our ignorance of this form of extremism is striking.

Wisconsin teaches us that the challenge that now presents itself is to understand what "pushes and pulls" citizens to commit violence in the name of rightwing extremism, and to develop an effective response. To do this, we must first start taking violence from the far right more seriously.