Hybrid warfare: what it is and what would need to happen for a conflict to break out

But what might trigger a direct military response to attacks attributable to a hybrid warfare strategy? According to Marrone, this would probably require ‘a hostile military presence and casualties’. The Atlantic Pact, which established NATO in 1949, “defines the scenario of a conventional armed attack, but recent strategic updates include cyber and space attacks as potential Article 5 scenarios, provided they have serious consequences. ‘The vulnerability of satellites, for example, affects the armed forces, civil aviation and financial systems,’ states the expert.

Even if the attack on Leipzig had resulted in casualties, however, triggering the collective defence provided for under Article 5 of the Treaty would have required the consent of the Council’s member states, which – taking into account the principle of proportionality – would have jointly assessed how to respond. For example, as Marrone points out, the violation of Polish airspace and that of other countries bordering Russia by a number of drones in recent months led to the convening of the North Atlantic Council under Article 4 of the Treaty and to measures aimed at strengthening the Alliance’s eastern flank. NATO’s response in these cases, however, was complicated by the fact that the drones were launched from ‘shadow’ ships or by internal operators.

According to Marrone, the hybrid attack on Leipzig Airport marks ‘an increase in the severity of the Russian threat’, confirming a trend that points to ‘an increase in the frequency and severity of incidents’. The incident has ‘prompted a political response and solidarity between the EU and NATO’, the expert added.

However, this was by no means an isolated incident. A report by the International Institute for Strategic Studies shows that between August 2024 and February 2026, 144 cases of European airspace violations by drones were recorded, and incidents occurring in the vicinity of airports disrupted air traffic, likely whilst gathering intelligence and testing Western reactions.

In the face of these threats, ‘the current European framework for countering drones is not yet equal to the challenge, despite the fact that NATO, the European Union and national governments are devoting greater attention to the issue: detection is patchy, legal authorities are fragmented, response options are often disproportionate, and the allocation of responsibilities remains too slow to ensure a timely deterrent’.

Drones are not the only weapon Russia has been accused of using to wage a hybrid war. The sea, as Marrone pointed out, is another key arena for the destabilisation tactics employed by Moscow, involving ‘shadow’ fleets and underwater sabotage.

“Civilian vessels with forged documents,” said the expert, “can smuggle Russian oil, can launch drones towards the coasts of the Baltic Sea and the North Sea, and can cause incidents involving subsea infrastructure (gas pipelines, oil pipelines, internet and electricity cables), whilst keeping the source of the activity obscure. European navies have already intercepted and penalised suspicious vessels in critical areas.”

Our country is among those most affected by attacks linked to hybrid warfare strategies. According to Marrone, ‘Italia has seen one of the sharpest increases in the G7 over the past two years’, whilst ‘long-term disinformation and propaganda are poisoning the debate, generating unfounded perceptions and conspiracy theories, and obscuring Russia’s responsibility’.

At a time when the gradual reduction of the US presence in Europe is under discussion, it will therefore be crucial to ‘move beyond off-the-cuff announcements and adopt a structured, phased approach, avoiding any signs of a disorderly withdrawal. This is not a total withdrawal, but a coordinated reduction. The combined capabilities must remain sufficient to deter Russian escalation,’ concluded the expert from the Institute of International Affairs.