Grey (zone) matter: Russia’s growing aggression in Europe

Since the start of the Russia-Ukraine war, already strained relations between Moscow and NATO – Ukraine’s main military backer – have sharply deteriorated. Rising tensions have, in part, occurred due to Russia’s intensified use of grey zone tactics – hostile measures that fall below the threshold for acts of conventional warfare. Most recently, this has involved a series of airspace incursions by Russian drones since September 2025, disrupting airport operations in Norway and Denmark, and prompting NATO forces to shoot down several drones over Poland. At least 38 similar incidents have been reported across Scandinavia, Belgium, and the Baltic states, and in response, the EU has outlined plans for the development of a 'drone wall' along NATO’s eastern flank. Meanwhile, Russian cyber operations against NATO countries have risen by 25 percent over the past year.

While grey zone activities have aimed to deter Western backing for Ukraine by disrupting societal functioning and weakening the alliance, escalating tensions between Russia and NATO also suggest that even if the conflict in Ukraine were to end, Russian grey zone aggression in Europe is unlikely to subside in the foreseeable future.

Pushing and probing NATO

Russia’s grey zone operations likely have several shorter- and longer-term goals. Amid widening rifts within NATO and among European states over how to respond to Russia, Putin has increasingly sought to take advantage of these fractures to weaken alliance cohesion and capabilities. Dealing with persistent sabotage and cyberattacks by Russian proxy groups, arson targeting warehouses, and drone incursions over sensitive sites and airports could divert governments’ focus away from Ukraine or collective defence commitments as they seek to strengthen domestic security. European governments will also need to convince voters suffering economic pressures and war fatigue that supporting Ukraine and regional defence spending is a priority. Consequently, some NATO members might be tempted to reduce their support for Ukraine to avoid further targeting, or domestic backlash over inflation and living costs.

Russia has further sought to exacerbate political and societal divisions as Europe experiences rising polarisation, often engaging in election interference and bolstering pro-Russia parties. Moldova’s parliamentary elections in September 2025, for example, saw significant Russian vote-buying, disinformation campaigns and cyberattacks to derail support for the ruling pro-European party. Russian interference not only drives domestic discord and policy deadlocks over spending and defence priorities, but also potentially paves the way for more sympathetic leadership in future elections.

A test of will and power

Europe has largely viewed Russia’s uptick in grey zone tactics as a probe to gather intelligence, testing both the willingness of member states to defend affected neighbours, and capabilities to detect and respond to threats. Airspace incursions and drone sightings have taken place over military bases and critical infrastructure like power plants, refineries, and arms factories, raising concerns among authorities that intelligence gathered now could inform future target selection. Meanwhile, Russian provocations have also occurred offshore, with Denmark reporting disruptions to navigation systems in the straits connecting the Baltic Sea to the North Sea, and Russian warships repeatedly pointing weapons and sailing dangerously close to Danish naval vessels. This provides the Kremlin with a valuable benchmark for assessing how NATO might react to a conventional Russian attack, particularly against smaller alliance members in Eastern Europe such as the Baltic states, should the war in Ukraine end and Moscow rebuild its military capabilities.

Notable Russian grey zone incidents in Europe (2024-2025)

Already at war?

From President Vladimir Putin’s perspective, Russia is already at war with the West. NATO’s growing membership in recent decades, which has included the likes of Estonia, Latvia and Lithuania, was viewed as a major strategic setback by the Kremlin, which has sought to maintain its influence over former Soviet Union countries. Since Russia’s invasion of Ukraine, Putin’s perceptions of Western hostility have only intensified. EU support for Ukraine – including military assistance and economic sanctions – as well as Europe’s boosted defence spending and military build-up – has been framed as confirmation of this hostility, with Putin commenting in early October that ‘All NATO countries are fighting us, and they’re no longer hiding it.’

This perception has implications for how Russia may decide to continue its hybrid warfare strategy on the European continent over the coming year. Its military efforts will likely remain focused on Ukraine despite its increasingly adversarial posture and Putin’s vows of a ‘swift response’ to perceived ‘provocation’ from Europe. Despite gradual territorial gains in Ukraine, Russia has still not achieved a decisive strategic breakthrough, and after sustaining extensive personnel and equipment losses over the past three years, it has limited capabilities to open a second front and engage in direct confrontation with NATO. Grey zone tactics, however, offer Russia an alternative means of pursuing strategic objectives and undermining Ukraine's allies, while avoiding the red line of war which could draw a stronger response from NATO than it may be prepared to deal with. It is no coincidence that countries such as Poland and Estonia – among Ukraine’s strongest allies – have been frequent targets of recent Russian grey zone operations, while Poland’s pro-Russia Visegrád partners, Slovakia and Hungary, have been spared. Against this backdrop, we are likely to see increased grey zone attacks on Ukraine’s backers in the coming months as Russia-NATO tensions boil.

A murky horizon

As Russia ramps up grey zone warfare, European states face both internal security threats, and the challenge of remaining unified and coordinated in responding to broader security concerns. While Putin’s decision-making process remains difficult to anticipate, often contradicting overt claims of peaceful intent, and the current trajectory of the Kremlin’s grey zone strategy could shift in response to various factors, Russia appears intent on staying below the threshold of open conflict with NATO for the time being. However, the growing frequency of Russian grey zone operations heightens the likelihood of accidents or miscalculations, particularly during airspace violations or naval provocations, with potentially escalatory consequences.

In the coming year, striking the right balance will be difficult for Europe: a forceful response risks escalation, while inaction may signal weakness, potentially inviting further aggression. Nevertheless, as a series of security conferences across Europe in 2025s has signalled, a stronger, more coordinated response is needed now more than ever – or Europe will need to come to terms with a new, grey normal.