Russia’s war in Ukraine and the possibility of Donald Trump winning a second term in office have made it increasingly urgent to refine the substance of the hitherto still mostly declaratory strategic partnership between the European Union and NATO. The outcomes of the recent NATO summit in Washington, DC, concerning the alliance’s cooperation with the European Union, were a missed chance and did not move the relationship forward.
The European Union’s security and defense have gradually advanced into areas previously reserved for NATO, such as defense capabilities development, military operations, and providing security guarantees for its members. This has led to growing calls for a close partnership between the alliance and the union. Over time, the NATO-E.U. partnership has become a central component of the broader European security governance, and an implicit division of labor has gradually emerged. Yet despite the tangible progress achieved over the last decade, there still is a considerable gap between the political rhetoric (laid down in joint declarations on bilateral cooperation in 2016, 2018, and 2023) and the day-to-day practice. Some argue that “NATO skepticism over the E.U.’s dabbling in defense runs deep” due to competition concerns. A similar feeling prevails among some E.U. countries, who fear that too close cooperation with NATO would undermine the European Union’s own security policy, leaving it dependent on the United States.
Yet, with warfare resurfacing on the European continent in February 2022 and U.S. security priorities redirecting toward the Indo-Pacific, the need to pursue a strategic partnership worthy of its name has never been more urgent. The lack of such a partnership threatens to undermine the security of the trans-Atlantic alliance — not least because the risk of duplication of effort in the absence of close cooperation is something neither side can afford due to resource scarcity.
In the current security environment of evolving challenges such as cyber threats and hybrid warfare that do not fit perfectly into traditional military or civilian categories, there will not be a neat division of labor between the European Union and NATO. Both organizations are inevitably going to be in the other’s way.
Picking up on the European Union’s recent announcement about the need to adopt a new forward-looking document encompassing the full spectrum of E.U.-NATO cooperation, we offer three concrete ideas for the new NATO and E.U. leadership on how to make the partnership operational. First, establish a joint military training mission supporting Ukraine. Second, create a better division of labor between the European Union and NATO in support of the development of the defense industry, including through legislative and financial mechanisms. Third, increase the interoperability of the armed forces among European and non-European NATO allies, including through military transport corridors, enhanced military logistics, and increased training efforts.
A Strategic Partnership Worth Its Name
Russia’s aggression against Ukraine has fundamentally changed the dynamics between the European Union and NATO. On the one hand, the war in Ukraine made the threat of military invasion in Europe more real, forcing both organizations to increase their efforts to keep their members safe. It also triggered the European members of NATO to increase their defense spending, which U.S. leaders long sought. In 2024, for the first time, the defense budgets of European NATO allies will amount to 2 percent of their combined gross domestic product. On the other hand, the paramount weight of Washington’s military aid to Kyiv has exacerbated resistance from parts of the U.S. establishment, which argue that the Indo-Pacific region — particularly the challenges posed by China — should be the top priority for U.S. security. This view manifested itself, among others, in the Republicans’ opposition to continuing aid to Ukraine and in Trump’s announcements about his plans to wind down aid to Ukraine and reduce the U.S. engagement in NATO.
Much has been written about the need for complementarity and division of labor, as neither NATO nor the European Union can deal with security threats based solely on their own assets and capabilities. Yet, a strict division of competencies is neither feasible nor desired. The two organizations have already expanded their activities into the traditional territory of the others, with the European Union advancing its defense capabilities and NATO developing civilian instruments. Threats like cyber attacks, terrorism, and hybrid warfare have blurred traditional boundaries between internal and external security, causing a growing need to address security-related issues through diverse instruments. Consequently, a certain degree of bureaucratic competition is inevitable as the European Union and NATO will inevitably overlap in their roles and responsibilities. However, it can be addressed by prioritizing the complementarity and interoperability of the two organizations’ resources and operations. Furthermore, duplication of resources, particularly in times of war, is still undoubtedly better than asset gaps.
Thus, partnership between the European Union and NATO is the best way to efficiently manage a single set of forces and resources, such as national defense budgets, personnel, and military capabilities. The main goal of such a partnership is not to divide work as efficiently as possible but rather to capitalize on and develop the strengths of both organizations.
Different ideas exist on how to advance the partnership. Some experts argue that a strategic partnership can be achieved by strengthening the European pillar in NATO and that, in fact, the United States should be vocally encouraging these efforts for practical and geopolitical reasons. However, this concept remains politically sensitive. Non-E.U. allies are wary of a more decisive voice of E.U. members in NATO, and countries on the Eastern flank fear that it might lead to decoupling from the United States, which would undermine their security. Others argue that the European Union should prioritize building its military capacity to act independently, particularly within Europe’s immediate neighborhood, and that such a European strategic responsibility would strengthen NATO.
Three Pillars of E.U.-NATO Partnership
Yet, there is a pragmatic way forward. We suggest a three-pillar approach focused on Ukraine, the defense industry, and the interoperability of forces. These proposals do not focus on a strict division of labor between the European Union and NATO. Instead, they embrace the relative financial, operational, and legislative strengths of the European Union to enhance the European contribution to NATO without decoupling from the United States.
Coordinating Efforts to Support Ukraine
The most vital area of strategic cooperation between the European Union and NATO is now coordinating efforts to support Ukraine in its fight against Russia. The NATO Washington summit brought three significant developments when it comes to the alliance’s engagement in coordinating support for Ukraine. NATO partially took over from the United States the role of coordinating lethal equipment deliveries to Ukraine through NATO Security Assistance and Training for Ukraine. NATO also announced the Pledge of Long-Term Security Assistance for Ukraine of €40 billion within the next year to provide military equipment, assistance, and training to Kyiv, and created the Joint Analysis Training and Education Center, the first-ever joint NATO-Ukraine institution.
To bring much-needed coherence to efforts to support Ukraine, these undertakings have to be implemented in close coordination with already existing E.U. measures. There are two ongoing E.U.-led security operations — E.U. Advisory Mission in Ukraine, which supports reforms in Ukraine’s civilian and security sectors, and E.U. Military Assistance Mission, within which Ukrainian soldiers are trained. The separate actions of the European Union and NATO must be coordinated in terms of goals, principles, and measures. Applying NATO standards in training Ukrainians through the E.U. Advisory Mission in Ukraine is essential in this direction. To increase the synergy effects and optimize resources, a joint E.U.-NATO training mission drawing on the E.U. Advisory Mission in Ukraine experience should be considered. Such an operation should be based on an adapted Berlin Plus agreement, which allows the European Union to draw upon NATO’s assets and capabilities for operations in which the alliance would not have to be militarily involved.
Also, when planning long-term support for Ukraine, it is necessary to consider the reforms that Ukraine must implement to prepare for NATO and E.U. membership. Close coordination of these processes is essential, especially given the Ukrainian administration’s limited capabilities and resources strained by the ongoing war. To this end, a NATO-E.U. task force should be created, consisting of officials of both organizations and representatives of Ukraine, to ensure the progress of the necessary reforms.
Accordingly, there is a growing need to better coordinate financial aid to Ukraine. Money has already been flowing through bilateral channels and within the Ukraine Facility — EU’s established financial assistance package of €50 billion for 2024–27 to support Ukraine’s recovery, reconstruction, and modernization. What makes the new NATO pledge essential in this context is its long-term character, which is very much needed and welcomed by Ukraine. Yet, considering the scarcity of financial resources, rendered more severe as the war continues, E.U. and NATO spending must be coordinated to maximize its effectiveness.
Wartime Economy: Strengthening the European Defense Industry
As the Russian war revealed the shortcomings of the European defense industry resulting from years of underspending, increasing its capacity is crucial for the effective operation of both organizations. And yet, we still do not see enough mutual cooperation in this realm beyond declaratory statements about NATO “taking mutual steps with the European Union to strengthen coherence and complementarity of respective efforts and relevant work.” Defense-industrial cooperation between the European Union and NATO needs to balance considerations of economic competitiveness and the push for Europe to produce more on its own. But more can still be done to unleash the synergies effect and capitalize on the inherent strengths of both organizations. The union should further advance the use of its financial and legislative mechanisms by putting real money on the table needed to promote the joint procurement of weapons and ammunition effectively. This task has been entrusted to the newly created E.U. defense commissioner, but whether the E.U. member states will provide the necessary financial resources to boost joint procurement remains uncertain. This problem might be partially solved by a greater involvement of the European Investment Bank Group, which is the financing arm of the European Union, in investments to strengthen the E.U. collective defense capabilities. Also, E.U. members should prepare for a wartime economy in which the defense industry must take more risks.
At the same time, while the European Union incentivizes capabilities development, NATO should remain responsible for capability targets and standardization. As former NATO Secretary General Jens Stoltenberg said, “You cannot have the E.U. and NATO present two conflicting lists of capability targets to Germany, Denmark, or Poland. So defense planning … has to be set by one and only one institution.” As for standardization efforts, their effectiveness is still insufficient. As NATO plays a leading role in this area, the European Union, using its legislative mechanisms for jointly funded capabilities, should support these efforts by obliging its members to comply with the rules established by NATO. So far, this has not happened.
Finally, Europeans must seek to ensure a greater output coherence between the NATO Defense Planning Process and endeavors undertaken by the E.U. European Defence Agency. Recognizing measures already in place, such as the E.U.-NATO Capability Group or the fact that the E.U. capability development process has recently started to take into account the NATO Defense Planning Process, there is a need to intensify these efforts to create additional incentives for the defense industries across Europe to advance to wartime mode. Concretely, the European Defence Agency, in close collaboration with NATO, could prioritize the development of strategic enablers, including strategic lift, air-to-air refueling, and operational intelligence. It would reduce European capability shortfalls and the excessive dependency on U.S. assets. Given the cost of these critical capabilities, European-wide cooperation and joint procurement that are well aligned with the NATO Defence Planning Process is the most effective way to go.
Interoperability of Forces
Finally, there is the need to advance the interoperability of forces, especially in a contested environment where adversaries challenge each other’s freedom of action. While NATO ultimately remains responsible for collective defense, it is vital for the European Union to do more in this domain. For instance, projects developed within the Permanent Structured Cooperation, aiming at boosting operational readiness by improving armed forces’ interoperability and capabilities in land, maritime, air, and cyber domains, should more effectively enhance European forces in NATO. The new NATO Force Model aims to maintain 500,000 troops in a high state of readiness, a goal achievable only with significantly increased involvement from European allies. A substantial European contribution is also essential to facilitate the necessary burden-shifting, ensuring European countries take greater responsibility for their own security, both financially and operationally.
While the current U.S. administration’s support for NATO remains “ironclad,” Europe cannot take it for granted. Strengthening European power in NATO is the best way of “Trump-proofing” the alliance and preparing it for a U.S. political and military shift to war in the Indo-Pacific. Three concrete steps will boost the interoperability of forces. First is accelerating work on improving military mobility in Europe. This should include creating additional military transport corridors similar to the one launched in January 2024 by Poland, Germany, and the Netherlands. By standardizing procedures across the European Union and NATO, such corridors would allow troops and equipment to move more easily across their territories to strengthen NATO’s eastern flank but also to enhance military and training support for Ukraine. Second is advancing cooperation on military logistics, particularly fuel storage, transportation, and distribution. This should be where NATO and the European Union cooperate closely, leveraging their strengths to create a resilient fuel supply chain across Europe. Third is to stress-test the work done on military mobility and logistics — joint training and exercises, including live military exercises, should take place regularly. Joint exercises should also include lessons learned from ongoing training with Ukrainians.
Conclusion
In today’s volatile security landscape, a robust NATO-E.U. partnership is not just desirable — it is imperative. There is no shortage of declarations of intent, mechanisms for institutional cooperation, and joint projects. What still seems to be lacking is political will at the highest level. The incoming NATO and E.U. leadership — including the new NATO secretary general, the E.U.’s high representative for foreign policy and security issues, and the E.U. defense commissioner — should decisively prioritize NATO-E.U. cooperation. Only through unwavering commitment at the highest political level can this partnership evolve from rhetoric to a genuinely strategic alliance capable of confronting the complex challenges that imperil American and European collective security.
Monika Sus is professor at the Polish Academy of Science and fellow at the Hertie School and the Robert Schuman Center for Advanced Studies at the European University Institute.
Dominik P. Jankowski is the deputy permanent representative of Poland to NATO.
The views expressed in this article are those of the authors and do not represent the position or views of their respective organizations/institutions.
Image: Dati Bendo via Wikimedia Commons
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