On April 29, two Jewish men were stabbed in north London in what British police declared a terrorist incident. Harakat Ashab al-Yamin al-Islamiya (HAYI), an "Islamic resistance" group that did not publicly exist two months earlier, immediately claimed responsibility. Since then, HAYI has claimed more than seventeen attacks across Europe.
HAYI is less a coherent terrorist organisation and more of a disposable instrument within an evolving hybrid warfare ecosystem. The group’s symbolism, propaganda, and operational patterns closely resemble those of Iran's Axis of Resistance network, marking it as the latest in a series of proxy actors the Iranian regime has deployed for gray zone warfare in Europe.
Given HAYI’s terrorist organizational trappings but hollow ideological affinity, it is reflective of a contemporary extremism landscape that is defined less and less by ideological boundaries. This means emerging threats are increasingly outpacing the conventional categories Western governments use to identify, prosecute, and prevent terrorism. Western counterterrorism efforts have historically been calibrated around the working assumption that ideologically committed actors organized into coherent movements are the central problem to be detected, disrupted, and prosecuted. In 2026, that assumption is now under strain. Recent expressions of violence signal a broader shift in how contemporary terrorism manifests. Terrorism is shifting from organizations with clear ideological boundaries toward fluid, transactional, and amorphous forms that the existing counterterrorism architecture was not built to recognize and therefore cannot defeat.
The Evolution of Ideology
The phenomenon of gray zone warfare, disruptive behaviour that sits below our traditional threshold of warfare, is by no means novel. Russia, in particular, has been strongly implicated in such activities, with over 150 hybrid incidents linked to Russia across Europe since its invasion of Ukraine in 2022. As part of this threat environment, the international community has observed the emergence of a new crime-terror nexus whereby hostile actors have increasingly cultivated ties with criminal entities, including both organized crime groups as well as ‘disposable’ local petty criminals who may not be fully aware of their involvement in geopolitical competition. Hostile state actors have leveraged criminal partners for hybrid activities in what is sometimes described as a “violence as a service” model. The goal of such hybrid tactics is to instill fear, provoke communal anxiety, strain security resources, and generate propaganda effects, all while avoiding thresholds that would provoke unified Western retaliation.
Read against this backdrop, HAYI looks at first glance like a recognizable case study in the genre. What makes the group different is the specific way it dresses these tactics in the costume of a terrorist organisation. The ideology is a wrapper. HAYI borrows the language, symbolism, and behavioural repertoire familiar from jihadist organisational practice without committing to ideology as a genuine organizational pillar. The result sits at the intersection of two trajectories: an expression of gray zone warfare on one hand, and an expression of how terrorism can manifest without clear ideological boundaries on the other. The latter creates complexities for how terrorism should be understood and engaged by policy makers.
Conventionally, terrorism analysis and response has organized around ideological taxonomies, with acts separated by the belief systems that inspire violence. This approach assumes terrorism emerges in distinct ideological waves that produced coherent movements with their own and identifiable strategic logics, mobilization pathways, grievance narratives, and organizational structures. Counterterrorism systems across Europe and North America were built around this assumption. The conventional model treated ideology as the primary mechanism of mobilization. The radicalization pathway, from grievance through ideological exposure to operational activity, became its organizing principle across countering violent extremism programs, intelligence prioritization, and prosecutorial strategy.
However, the extent to which this view continues to hold analytical value has been increasingly questioned by both terrorism scholars and practitioners. Rather than terrorism defined by clear ideological boundaries, contemporary terrorism dynamics are characterized by greater fluidity and diversity. Driven in part by the virtualization of extremism, and of society more broadly, the current threat environment is shaped by younger lone attackers whose radicalization occurs primarily online and at accelerated speed, combining fragments of political ideas with personal grievances that defy clear ideological categorization. Coherent organizations with identifiable membership, leadership, and doctrine are no longer the central operational unit for how terrorism emerges in Western countries. They have been replaced by fluid online milieus, post-organizational networks, and individuals self-assembling worldviews from the available material. Terms such as mixed, unstable, unclear ideologies, salad-bar or pick-and-mix extremism have emerged to capture the individually assembled and ideologically promiscuous nature of contemporary radicalization.
HAYI adds a further dimension to this already heterogeneous ecosystem. The lone actor problem of the past decade described ideologically thin individuals operating without organizational backing. HAYI describes something close to the inverse. The operational signature is recognizably terrorist, including symbolic targeting of religious minorities, claim videos, and political demands. But the recruitment infrastructure is transactional, the perpetrators are interchangeable, and the organizational form is deliberately disposable. Ideology, in this case, is not the cause but the cover.
Taken together, the most recent iterations of violent extremism highlight a terrorism landscape in which the relationship between ideology, organization, and violence has become genuinely unstable.
This is not to say ideology has ceased to matter. Ideology continues to shape, constrain, and facilitate violent behaviour, and ideologically coherent organisations continue to motivate and structure violent action across the contemporary threat landscape. The argument is not that terrorism is leaving ideology behind. It is that the relationship between ideology, organization, and violence has become more variable than the conventional model assumed, and that counterterrorism practice needs to understand how ideology interacts with the wider set of factors that produce political violence, including financial incentive, social vulnerability, online ecosystem dynamics, and state strategic interests, rather than treating ideology as a monolithic explanatory variable. The end result is an emergent terrorism environment that generates significant complexities for counter-terrorism practitioners, not that their jobs were ever simple or straightforward.
The Task Ahead
How European jurisdictions have responded to HAYI illustrates this complexity. Dutch authorities charged suspects in the Rotterdam synagogue case with arson with terrorist intent. French authorities charged the suspects in the foiled Paris Bank of America plot with criminal terrorist conspiracy and attempted destruction in connection with a terrorist enterprise. British authorities, by contrast, initially charged suspects with standard arson and criminal damage offenses, while more recently designating the Iran Revolutionary Guard Corps as a terrorist organisation. The targeting pattern, ideological framing, and external claim of responsibility are common to all three jurisdictions. Same campaign, same operational signature, three different legal frames. These divergent responses reflect the absence of any single coherent approach within the existing European legal architecture for how a campaign like HAYI's should be addressed.
Western governments and security services have not been blind to this shift. Ken McCallum, the director general of the United Kingdom's domestic counter-intelligence and security agency (MI5), publicly described "more volatile would-be terrorists with only a tenuous grasp of the ideologies they profess to follow" and named the disposable-agents model directly in his 2025 threat update. Europol's 2025 Terrorism Situation and Trend Report explicitly identifies the hybridization of ideologies and the growing involvement of minors in violent extremism. The diagnosis is increasingly shared across European security and intelligence services.
What has not yet followed is the structural translation of that diagnosis into legal frameworks, prosecutorial strategy, and prevention architecture. The divergent legal responses to HAYI across the United Kingdom, the Netherlands, and France are the most concrete evidence of this lag. Recognition at the intelligence level has not produced consistent legal treatment at the prosecutorial level. The analytical categories used to organize terrorism reporting, including the European Union’s annual Terrorism Situation and Trend report, still rest on ideological taxonomies even when they are acknowledged by security practitioners as inadequate. Prevention programmes are being reformed in principle but the institutional weight of fifteen years of ideology-centered design will not shift quickly.
The task ahead is less about discovering the problem than about closing the gap between what is now recognized and what is operationally adapted. Security institutions will either need to broaden existing concepts of terrorism and radicalization to accommodate fluid, transactional, and state-directed forms of violence, or new frameworks will need to be developed alongside those previously established. Legal frameworks that currently force ambiguous cases into single statutory categories will need to bridge across terrorism, foreign interference, and organized crime authorities. Prevention work calibrated around ideological signatures will need to extend toward the recruitment ecosystems where contemporary perpetrators are increasingly found, including encrypted platforms, financial intermediaries, and online marketplaces for low-skilled violence.
None of this is straightforward, and the structural burdens of ideology-centered design will act as a barrier. But the cost of inaction is already visible. The HAYI brand will likely be retired and replaced within months. The model it represents will not. If Western institutional response continues to lag the diagnosis, the next franchise will exploit the same gaps.
James Paterson, Ph.D., is a research associate at the Lowy Institute’s Transnational Challenge program. He holds a Ph.D. from Monash University, and his research focuses on insurgent adaptability and organizational dynamics.
The views expressed are those of the author and do not reflect the official position of the Irregular Warfare Initiative, Princeton University’s Empirical Studies of Conflict Project, the Modern War Institute at West Point, the Department of the Army, the Department of War, or the United States Government.
Main photo from Wikimedia Commons.
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