Russia’s Hybrid Campaign: A Test of Europe’s Unity and Deterrence

Russia’s hybrid campaign is testing Europe’s ability to remain united under pressure. This matters beyond the grey zone: how Europeans respond today will shape Moscow’s expectations of whether Europe will act together in a future conflict. It shapes the credibility of European deterrence.

Russia’s Hybrid Campaign: A Test of Europe’s Unity and Deterrence

Russia’s hybrid warfare in Europe has entered a new phase. The scope and nature of attacks are changing. Russia has chosen to further escalate, both in Ukraine and elsewhere in Europe. In doing so, the Kremlin is taking more risks, with attacks on railway infrastructure, explosives at airports and drones from its shadow fleet. At the same time, Europe’s response is changing. European governments have been relatively reluctant to point to Russia, but recent statements on attribution and the language of deterrence suggest a more assertive approach.

Attacks below the threshold of war provide repeated tests of European cohesion. As Europe assumes greater responsibility for its own security, that unity will become an important determinant of credible deterrence. Amid growing divisions with the United States, Europe must therefore also confront another vital challenge: managing its own internal differences.

The daily reality of hybrid war in Europe

Russia’s hybrid campaign against Europe predates the full-scale invasion of Ukraine, with major events like the large-scale cyber-attack on Estonia in 2007 and the Skripal affair in 2018. Since 2022, this campaign has significantly accelerated, including sabotage operations against Europe’s critical infrastructure.

This year, Russia has further escalated. While violations of European airspace still made headlines last year, today they have become a common occurrence. Russia’s escalation in Ukraine also seeks to intimidate the latter’s European supporters, as illustrated by the drone attack on a Warsaw-bound train near the Polish border. There are also increased attempts to target companies that support Ukraine, such as the August arson attack on Milrem Robotics in Estonia.

Beyond reckless behaviour

For a long time, such attacks were politically treated as temporary and limited in nature. European leaders labelled them as incidents, or a series of incidents. They called out Russia’s “reckless” behaviour, as if Moscow were acting on impulse rather than pursuing a calculated strategy to test Europe’s limits.

Yet Europe’s cautious approach is beginning to give way to a more assertive response. A turning point in strategic communication was the Leipzig attack. After a few weeks of investigation, Germany attributed the attempted drone attack to Russia. European leaders echoed Germany’s statements, showing that a unified response, at least in rhetoric, is possible. But such unity is not a given. The events in Ceuta a month earlier demonstrated that a hybrid crisis can also expose political divisions across Europe. An estimated 80,000 people crossed irregularly from Morocco into the Spanish enclave. Analysts linked the crisis to a recent Spanish-Algerian diplomatic visit and pointed to Morocco’s history of using migration as a tool of political pressure. Instead of collectively expressing solidarity with Spain, European leaders publicly blamed Spain. They were also quick to question the rules of the Schengen area, one of the foundations of the union we are trying to protect.

Europe’s internal fault lines

Ceuta illustrates a broader challenge: European states remain divided not only over how to respond to security threats, but also over what they consider a threat in the first place. Our recent study reveals the extent of this divergence, providing the first comprehensive assessment of how threat perceptions across Europe have changed since Russia’s full-scale invasion of Ukraine[1]. While Northern and Eastern European countries perceive Russia as a potential existential threat, some Western and Southern European states do not even prioritise Russia as their main national security challenge. As Spain’s security concerns centre largely on Morocco and Europe’s Southern Flank, Sánchez has argued that “Russian tanks won’t reach the Pyrenees”.

This structural and political diversity is reflected in how governments communicate about possible Russian escalation. The Danish Defence Intelligence Service recently warned of a “low but growing risk” that Russia could launch a limited military attack against one or more NATO countries bordering Russia in the coming months. Other countries have also sounded the alarm: the chief of the Dutch armed forces, General Onno Eichelsheim, warned that Europe is “facing a window of vulnerability until 2030”, and Czech intelligence chief Michal Koudelka suggested that a small-scale invasion of NATO territory could occur.

Others have been more reluctant to adopt this rhetoric. Finnish President Alexander Stubb recently argued that he saw neither evidence nor facts to support predictions that Russia would attack NATO within the next few years. Several officials in Estonia also warned allies about the risks of constant speculation. While both countries take the Russian threat very seriously, they weigh the implications of such public warnings differently.

Differences have also emerged over how European governments would respond to a Russian escalation. “If Russia attacked us and we took our gloves off, I think we would defeat Russia quite quickly,” Polish Foreign Minister Rados?aw Sikorski argued in mid-September. One week later, the prime minister of neighbouring Slovakia, Robert Fico, stated that “I do not want Slovakia to be part of any military conflict because of some Article 5.” Fico’s position is exceptional, but it does show the risk that populist leaders can undermine European unity. And with Europe heading into a consequential election year and populist parties polling strongly in several countries, his position may not remain as exceptional as it is today.

Hybrid warfare exploits Europe’s internal fault lines

For Moscow, Europe’s internal fault lines create opportunities. This is particularly important in the hybrid domain. Ambiguity is inherent to attacks below the threshold of conventional war. Governments must agree on what happened, who was responsible, how serious an attack was and what response is proportionate. Different threat perceptions and political priorities can make this more difficult. At the same time, creating and exploiting these political divisions is itself part of hybrid warfare.

Every hybrid incident provides Moscow with information about European political unity. If targeting one European country produces disagreement among its partners over what happened, whether Russia was responsible or whether a collective response is warranted, this sends a very different signal from one in which European governments rapidly close ranks.

The credibility of European deterrence depends not only on military capabilities, but also on the perceived unity of political will behind them. Repeated failures to demonstrate unity below the threshold of war risk raising doubts about whether that unity would hold above it. Conversely, a unified response to hybrid aggression signals that targeting one European state will not drive a wedge between European governments.

Unity without uniformity

Strategic differences across Europe will persist. The challenge is to prevent these differences from standing in the way of a united response when one of its members is attacked. We should not normalise Russia’s hybrid campaign, nor should we let it divide us.

This is where von der Leyen’s proposal for “Europe’s own Article 4” could prove useful. Such an Emergency Security Protocol, as announced in her State of the Union, would allow a member state facing a hybrid attack to coordinate a European response. Its value would lie in facilitating coordinated communication and collective action despite different underlying threat perceptions and assessments of possible escalation scenarios.

Institutionalising such consultation would also contribute to conventional deterrence. Moscow should expect that targeting one European state will trigger a coordinated European response rather than create an opportunity to divide its partners. Political unity is essential for credible deterrence. How Europeans respond together to attacks below the threshold of war will help determine whether Moscow believes they will stand together when that threshold is crossed.

[1] https://www.tandfonline.com/doi/full/10.1080/13523260.2026.2687095

(Photo credit:  © European Union, 2026)