While there is no universally accepted definition, a lone wolf terrorist is usually defined as a terrorist who operates on their own without outside help. Many of the definitions vary about key aspects, causing definitional problems and issues in comparative study, compounded by terminology issues. Other equivalent terms, mostly used interchangeably, include lone operator terrorism, freelancers, freelance terrorism, solo terrorists, solo actors, solitary, lone offenders, lone avengers, and individual terror cells, among others.
Other definitions include terrorists who operated solely on their own, but also those who committed an act themselves while being directed by a larger organization, groups of two and small cells. Researcher Christopher Hewitt argued that a terrorist group could only be defined at four or more people, and that if a group was made up of three or fewer members they were still lone wolves, while Paul Gill argued that dyads would qualify. Other scholars criticized this as an "oxymoron" and as negating the entire concept. It is not a legal term or a social science concept; some researchers have argued that the term is constructed by the actors themselves as well as the media, and argue the general concept of lone wolf terrorism is not useful. Furthermore, the distinction of non-ideologically motivated crimes including other spree killings versus terror act can often be difficult to define, and some individuals who were called lone wolf terrorists were found to have acted without ideological motivation. Terrorism itself is difficult to define for similar reasons.
Lone actor terrorists are ideologically driven, with political or religious motives, and are intended to create fear and influence public opinion. Lone wolf terrorists may sympathize with and consider themselves part of larger groups, but they are usually not active participants. The links between lone wolves and actual terrorist groups tend to be informal and conducted online.
Compared to the general population, lone wolf terrorists are significantly more likely to have been diagnosed with a mental illness, although it is not an accurate profiler. Studies have found that roughly a third of lone wolf terrorists have been diagnosed at some point in their life with a mental illness. This puts lone wolves as being 13.5 times more likely to suffer from a mental illness than a member of an organized terrorist group, such as al-Qaeda or ISIS. Environmental factors such as relationships with those belonging to a terrorist group, social isolation, and various stressors mediate the relationship between mental illness and lone wolf terrorism. Mental health challenges are thought to make some individuals among the many who suffer from certain "psychological disturbances", vulnerable to being inspired by extremist ideologies to commit acts of lone wolf terrorism. An alternative explanation is that terrorist groups reject those with mental illnesses as they pose a security risk, creating a selection bias.
Lone wolf attacks are rarely committed solely without help by genuine loners. A 2011 typology based on an analysis of lone wolf operations by Raffaello Pantucci defined four categories of lone wolf: Loner, Lone Wolf, Lone Wolf Pack, and Lone Attacker. As defined in his typology:
In many cases, such as with Alex Curtis, the lone wolf never has personal contact with the group they identify with. As such, it is considerably more difficult for counter-terrorism officials to gather intelligence on lone wolves, since they may not come into contact with routine counter-terrorist surveillance. In the United States, lone wolves may present a greater threat than organized groups. Some groups actively advocate lone wolf actions. In news analysis of the Boston Marathon bombing, the Al-Qaeda activist Samir Khan, publishing in Inspire, advocated individual terrorist actions directed at Americans and published detailed recipes online.
Historian Richard Jenson says the years 1878–1934 were the era of anarchist terrorism and should be considered the classic age of "lone wolf" or leaderless terrorism. Anarchists rejected authoritarian, centralized control over acts of planned violence as well as over anything else. Jenson says there were hundreds of violent anarchist incidents during this period most of which were committed by lone individuals or very small groups without command structures or leaders. Since 1940, there have been around 100 successful lone wolf attacks in the United States.
Most 20th century lone wolf attacks were ineffective and did not have a large impact. An early case was Joseph Tommasi of the National Socialist Liberation Front promoted that, since the public would never become a revolutionary force, they could only have an impact if individuals took up arms; several members of his group did as he suggested, but there was little impact except jail sentences for the perpetrators. In its widespread usage in the far-right, it emerged in a period of trouble for the American movement. The movement was scattered between several smaller groups in the 1980s; in the 1960s they had been relatively centralized in the American Nazi Party led by George Lincoln Rockwell.
In contrast to the European far-right, which was largely a law enforcement issue and not much of a threat to the state (though there were one off cases of far-right lone wolves in Europe, e.g. Swedish serial killer John Ausonius), the American far-right had immense amounts of weaponry at its disposal. Many of these far-right groups became explicitly revolutionary: The Covenant, the Sword, and the Arm of the Lord at one point issued a declaration of war on the US government, while The Order embarked on a string of murders and robberies. Joseph Paul Franklin, a racist serial killer who was expelled from the American Nazi Party, became an early lone wolf killer, killing several people over a period of two decades; however, he never attributed his crimes to an ideology while committing them, so his crimes had no actual terrorist impact until after he was caught.
The US government, made aware of the danger of such groups due to the actions of the Order, cracked down on many far-right organizations. After the Waco siege, the Ruby Ridge standoff, and several other instances the far-right became even more paranoid, and civil suits filed by groups like the Southern Poverty Law Center (SPLC) eliminated or affected many of the groups. Other groups were infiltrated, by both government agents and organizations like the Anti-Defamation League. This led to distrust and discontent spreading among these movements. As a result of these organizational problems, white supremacist Louis Beam promoted the similar tactic and his particular conception of leaderless resistance, in an essay titled "Leaderless Resistance", where he argued that due to the government persecution of organized movements a solution could be found in "non-organization".
Towards the end of the 20th century, the leaderless resistance concept would morph into the lone wolf idea. The popularization of the term "lone wolf" in reference to terrorism probably began in the 1990s among the white supremacist movement. "Lone wolf" as a term in reference to this concept was effectively coined by white supremacists Alex Curtis and Tom Metzger in the 1990s; both encouraged other white racists to commit crimes for tactical reasons. Metzger was the leader of the White Aryan Resistance, one of the groups affected by the civil suits by the SPLC, while Curtis, one of the far-right's earliest popular figures online, was the operator of a website called the Nationalist Observer out of San Diego.
Unlike Beam's leaderless resistance concept, which allowed for small cells as part of the model, Metzger and Curtis preferred lone actors. George Michael noted Curtis as then being the "most vociferous" promoter of the lone wolf approach. Curtis argued against formal group membership and meetings, given the easy infiltration of them and the ability of others to file legal action against dissident groups; "lone wolf" action would avoid incriminating the group. He promoted a two tiered system, with a propaganda wing to encourage the lone wolves alongside the actors themselves. Curtis's rhetoric brought him to the attention of authorities, and he became the subject of a two-year FBI and San Diego Police Department investigation in 1998, called Operation Lone Wolf. As a result of the FBI investigation's name, the "lone wolf" terminology became established in referring to lone wolf terrorism.
Lone wolf attacks became more prominent in the 21st century. While initially popular among white supremacists, the method was used increasingly among Islamic terrorists in the early 2000s, partially through example in other attacks and later through promotion by the Islamic State. Jewish extremists also used the strategy, e.g. Yigal Amir who assassinated Prime Minister of Israel Yitzhak Rabin.
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Michael 2012, p. 47. - Michael, George (2012). Lone Wolf Terror and the Rise of Leaderless Resistance. Nashville: Vanderbilt University Press. ISBN 978-0-8265-1855-2.
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