The idea of the crime-terror nexus is not new. The term emerged in the early 1990s after the collapse of the Soviet Union and the birth of the Information Age. Amidst shifting geopolitics and newfound transnational reach, non-state actors adapted criminal modus operandi to further their aims.
As early as the 1980s, during the rise of Pablo Escobar and the Colombian drug cartels, scholars tried to define ‘narco-terrorism’ and debated whether it represented a true case of blurring criminal-terrorist lines. In more recent years, the term ‘criminal insurgency’ has been used to describe the way in which criminal organisations represent strategic security threats to states.
Moreover, it is no secret that the Taliban have at times depended on Afghanistan’s heroin production; that Hezbollah has invested into South America’s illicit narcotics industry since the 1980s; and that groups like the Irish Republican Army (IRA) have been involved in smuggling petrol, cigarettes, and counterfeiting consumer goods.
 John Picarelli, ‘Osama bin Corleone? Vito the Jackal? Framing Threat Convergence Through an Examination of Transnational Organized Crime and International Terrorism’, Terrorism and Political Violence, Vol 24, Issue 2, 2012, p.183. Also refer to Sylvia Longmire and John Longmire, ‘Redefining Terrorism: Why Mexican Drug Trafficking is More than Just Organized Crime’, Journal of Strategic Security, Vol 1, Issue 1, 2008, pp.35-51.
 John Sullivan, ‘Criminal Insurgency: Narcocultura, Social Banditry, and Information Operations’, Small Wars Journal, December 2012, pp.1-13. Sullivan uses Los Zetas of Mexico as an example of a criminal insurgency.
 Ron Moreau, ‘The Taliban’s New Role as Afghanistan’s Drug Mafia’, Newsweek, 12 June 2013; Matthew Levitt, ‘Iranian State Sponsorship of Terror’, Testimony of Levitt, Joint Hearing of the Committee on International Relations, 16 February 2005; Levitt, ‘Hizbullah Narco-Trafficking: A growing cross-border Threat’, The Washington Institute, September 2012; ‘Want to know what the IRA is now? It’s a trust fund’, The Irish News, 27 August 2015.
In our view, the crime-terror nexus is a useful concept, but its nature and dynamics are different from how it has traditionally been conceived. What we have observed in the case of jihadist recruits in Europe is not the convergence of criminals and terrorists as organisations but of their social networks, environments, or milieus.
In other words: rather than being one or the other, criminal and terrorist groups have come to recruit from the same pool of people, creating (often unintended) synergies and overlaps that have consequences for how individuals radicalise and operate. This is what we call the new crime-terror nexus.
Groups vs Networks
One of the most prominent pioneers of the notion of a crime-terror nexus is Tamara Makarenko. On her ‘crime-terror continuum’, she identifies three areas of the nexus: cooperation, convergence, and transformation.
At one end, criminal and terrorist groups cooperate, either in limited, transaction-based alliances, or in more sophisticated coalitions. Nearing the middle, convergence indicates when groups adapt skills belonging to the other group. They become hybrid criminal-terrorist groups, each utilising criminal or terror tactics to further their disparate motivations. Finally, at the other end of the continuum lies transformation, in which a group has completely transformed into the other by way of a shift in motivation. 
Similarly, Louise Shelley and John Picarelli have examined ways in which terrorists adapt criminal methods. They found that in the majority of cases, terrorist groups appropriate activities for tactical reasons.  Steven Hutchinson and Pat O’Malley support this claim, and indicate that any cooperation is a last resort. 
While they agree that today’s terrorists will choose to profit from almost any illicit opportunity, they argue that most groups do not retain strategic, entrepreneurial ambitions. Therefore, symbiotic relations, or long-term alliances between these groups, are unlikely.
None of these accounts reflect how terrorist structures, radicalisation and recruitment have changed. Jihadist groups such as al-Qaeda and Islamic State operate not wholly as top-down organisations but also in the form of dispersed, autonomous cells who pursue strategies and tactics that are not always – or necessarily – aligned with those of their leadership. The traditional literature has failed to recognise this, and – consequently – tells us little about the merging of criminal and terrorist milieus in places like the suburbs of Paris or Brussels.
 Tamara Makarenko, ‘The Crime-Terror Continuum: Tracing the Interplay between Transnational Organised Crime and Terrorism’, Global Crime, Vol 6, No 1, 2004, pp.129-145.
 Louise Shelley and John Picarelli, ‘Methods and Motives: Exploring Links Between Transnational Organized Crime and International Terrorism’, Trends in Organized Crime, Vol 9, No 2, 2005.
 Steven Hutchinson and Pat O’Malley, ‘A Crime–Terror Nexus? Thinking on Some of the Links between Terrorism and Criminality’, Studies in Conflict Terrorism, Vol 30, Issue 12, 2007, p. 1096.
Ideology vs Profit
Another misconception… is the ‘profit vs. ideology’ dichotomy: while criminal organisations aim to profit, terrorist groups pursue ideological objectives.  For a long time, this dichotomy fomented conclusions that Islamist or jihadist groups would not engage in criminal activity as it is contrary to their ideological aims.  As Daniella Bove-LaMonica stated, ‘Research shows that the international community is historically reluctant to do anything more than speculate on Al-Qaeda’s involvement in organised crime’. 
It is only relatively recently that scholars have started to reinvestigate the extent to which al-Qaeda affiliates are invested in criminal markets. Samuel Aronson, for example, concluded that the aims of Al-Qaeda in the Islamic Maghreb – a group which has engaged in the smuggling of cigarettes and counterfeit products since its founding – are alternating from criminal to ideological. 
Even so, Chris Dishman and other prominent advocates of the crime-terror nexus seem reluctant to accept that groups – and the various networks within them – can pursue a diversity of aims. In his own words, ‘drug barons and revolutionary leaders do not walk on the same path to success’. 
 Santiago Ballina, ‘The-Crime Terror Continuum Revisited,” Journal for Policing, Intelligence and the Power of Informal Networks’, Vol 6, No 2, 2011, pp.121-124.
 Steven Hutchinson and Pat O’Malley, ‘A Crime–Terror Nexus? Thinking on Some of the Links between Terrorism and Criminality’, Studies in Conflict Terrorism, Vol 30, Issue 12, 2007, pp.1095-1106; Chris Dishman, ‘Terrorism, Crime, and Transformation’, Studies in Conflict & Terrorism, Vol 24, No 1, 2001, pp.43-58.
 Daniella Bove-LaMonica, ‘Al-Qaeda and Drug Trafficking, a Dangerous Partnership’, Policy.Mic, 4 June 2011.
 Refer to Samuel Aronson, ‘AQIM’s Threat to Western Interests in the Sahel’, CTC Sentinel, 7 April 2014, p.9.
 Chris Dishman, ‘Terrorism, Crime, and Transformation’, Studies in Conflict & Terrorism, Vol 24, No 1, 2001, p.45.
Rich vs Poor
For terrorism researchers, one of the main obstacles to investigating crime-terror convergence has been the conventional wisdom that terrorists are not poor and uneducated, but – rather – originate from middle and upper class milieus who are rarely, if ever, involved in ‘petty crime’. This notion originates in the early 1980s when Saad Eddin Ibrahim, an Egyptian sociologist, discovered that a high percentage of imprisoned Egyptian Islamists were engineers and doctors who came from well to do families. 
Marc Sageman, the American former CIA operative turned academic, arrived at similar conclusions in the early 2000s: of the 172 profiles of al-Qaeda members in his sample, less than a third were ‘lower class’, and nearly 40 per cent had university degrees.  The fact that Osama bin Laden, the long-time leader of al-Qaeda, was the son of a millionaire, and that many of the 9/11 attackers were university students with no criminal records perfectly fits this narrative.
As a result, and despite growing evidence to the contrary, researchers have historically shown little interest in the convergence of criminal and terrorist milieus. With the exception of prisons, which have long been identified as potential ‘breeding grounds’ for terrorism, most researchers have been content to reiterate the notion of ‘middle class’ terrorism; insisted that overlaps between terrorist and criminal milieus were ‘anecdotal’ rather than systemic; or dismissed the entire idea of terrorism being correlated, in certain instances, with any social, economic or demographic factors as ‘futile’, repeating the oft-stated mantra that there is ‘no one profile’ of a terrorist. 
The consequence of these various failures of imagination has been that the convergence of criminals and jihadists in Europe has gone largely un-noticed: while the merging between criminal and terrorist milieus in Europe is real, few scholars have – thus far – shown any interest in studying it.