NATO and the European Union, a difficult partnership: between inertia, cooperation and signs of rupture

With the war in Ukraine and Donald Trump’s return to the White House, new scenarios have opened up in the partnership between NATO and the European Union. The EU’s dependence on the Atlantic Alliance, however, remains enormous due to the insufficient security capabilities of European countries. This is highlighted by Nicolò Fasola and Sonia Lucarelli, two scholars at the Department of Political and Social Sciences - SPS of the University of Bologna, in an analysis published in the volume "The War in Ukraine, NATO, and European Defence".

"European states face the need to develop autonomous defence and deterrence capabilities, but at the same time they see this possibility opposed by public opinion, limited by spending capacity and not imminent in time", explains Sonia Lucarelli. "It may therefore be necessary to show institutional creativity and rethink the European security architecture in an innovative way, combining the interests, abilities and political will of those countries that genuinely wish to contribute to European security and defence in a cohesive manner".

With Russia’s invasion of Ukraine in 2022, NATO and the European Union managed to create synergies to support Kyiv’s sovereignty and ensure European security. On the one hand, the Atlantic Alliance has taken on the role of the main guarantor of collective defence and deterrence on the eastern flank, while on the other the EU has implemented economic sanctions to weaken Russia’s war effort and innovative financial instruments to support the functioning of Ukrainian institutions.

This positive experience of cooperation – the scholars note – has, however, been called into question by the “America First” approach of the new US government. In addition to strongly urging individual allies to significantly increase their contributions to NATO, the Trump Administration has shown little interest in a “just resolution” of the Ukrainian conflict. The United States is aiming to disengage from Europe and to reallocate military resources to other regions, starting with the Middle East and, in the long term, to the Indo-Pacific, to counter the perceived strategic threat posed by China.

As a result, European countries have begun to discuss the formation of ad hoc coalitions to ensure the security of Ukraine and Europe, and have implemented new financial measures at EU level to support the rearmament of member states.

“However, there are still strong constraints on what European countries and the EU itself can do to ensure their own security, both in collaboration with NATO and independently”, explains Nicolò Fasola. “This is both because European governments have different attitudes towards the current US Administration, and because a hypothetical Western inability to keep the promises made to Ukraine, in effect allowing its territorial dismemberment, would deal a severe blow to the credibility not only of NATO but also of the EU.”

The results of the ReArm Europe plan (now renamed Readiness 2030), which the EU has developed with the aim of creating cohesive and efficient European defence, are still, at best, a long way off. Until then, the European Union remains dependent on NATO to ensure its defence capability.

“It will take several years to bridge the gaps in European security, not to mention that a large part of European public opinion is reluctant to support a major investment in defence at the expense of other social investments”, says Lucarelli. “Moreover, it has proved very difficult to establish a functioning European procurement system, and it is therefore likely that EU countries will continue to purchase defence systems from non-European, i.e. American, suppliers.”

The analysis authored by Nicolò Fasola and Sonia Lucarelli is entitled “The NATO–EU Partnership between Inertia and Disruption” and was published in the volume “The War in Ukraine, NATO, and European Defence” (Routledge, 2026).