Europe’s Strategic Trap: Why Russia’s Sub-Threshold Coercion Is Succeeding and How to Stop It

What if Russia’s sabotage, drone incursions and other sub-threshold attacks across Europe are not isolated incidents, but part of a coherent strategy?

Since Russia’s full-scale invasion of Ukraine, European states have faced a sustained campaign of assassinations, sabotage, drone incursions, and other attacks designed to remain below the threshold of major war. This new HCSS report argues that these actions are not random incidents or examples of vaguely defined “hybrid warfare”. Rather, they form a deliberate coercive strategy aimed at reducing European military and financial support for Ukraine.

The report by Markus Iven, Ethan Mansfield, Nicole Eichstaedt and Tim Sweijs finds that Russia’s campaign is selective, targeting states that support Ukraine while avoiding those that do not. Its objective is to influence political decision-making in Europe by increasing the costs and risks associated with supporting Ukraine.

Through case studies of Russian drone incursions in Belgium and Poland in 2025, the authors show how these operations coincided with key decisions on Ukraine support and successfully shaped European behaviour.

According to the report, Europe is caught in a strategic trap. Russia can choose the time, place and method of attack, while European governments must protect an expanding range of potential targets. As a result, Europe’s current approach, centred on deterrence by denial and defensive resilience measures, is proving insufficient and, in some cases, strategically counterproductive.

To break out of this trap, the authors propose a “4D Strategy” built around four complementary lines of effort:

• Deny Russia the ability to coerce Europe into reducing support for Ukraine.
• Disrupt Russian intelligence networks and command structures operating in Europe.
• Degrade the capabilities and resources that enable Russia’s sub-threshold attacks.
• Deter future attacks through credible punishment.

The report’s central recommendation is that every Russian sub-threshold attack should trigger additional support for Ukraine and impose greater costs on Russia’s war effort. By reversing the logic of coercion, Europe can make Russia’s campaign self-defeating and strengthen both Ukrainian and European security.

Authors: Markus Iven, Ethan Mansfield, Nicole Eichstaedt and Tim Sweijs.

With thanks to Frank Bekkers for his contribution.

The research for and production of this report has been conducted within the PROGRESS research framework agreement. Responsibility for the contents and for the opinions expressed, rests solely with the authors and does not constitute, not should be construed as, an endorsement by the Netherlands Ministries of Foreign Affairs and Defence.