How Europe Can Build Ukraine’s Future Force

How Europe Can Build Ukraine's Future Force

Photo: SERGEI SUPINSKY/AFP via Getty Images

Capability Requirements

From an economic perspective, replacing U.S. military support is manageable. The European Union would need to spend an additional 0.12 percent of its GDP to replace U.S. military support for 2024 (roughly $24 billion in nominal terms). The challenge lies not in aggregate spending but in providing specific capabilities through consistent and coherent deliveries.

In the short term, Ukraine needs sustained flows of large-caliber artillery ammunition and air defense systems-areas where annual demand far exceeds European production capacity. Ukrainian demand for air defense interceptors alone is estimated at around 4,800 units annually, well beyond current European production capacity. Beyond immediate battlefield requirements, Ukraine must strengthen its indigenous DIB and integrate it with Europe's, while balancing training and force generation against acute labor shortages.

Some U.S.-produced capabilities will be difficult to replace in the short term. The Kiel Institute estimates that Ukraine's biggest dependencies on U.S.-produced weapons as of March 2025 were in rocket artillery (86 percent of weapons for Ukraine were U.S.-produced), howitzer ammunition (82 percent U.S.-produced), and long-range anti-aircraft systems (70 percent U.S.-produced). Among heavy weapons, Ukraine's reliance on U.S.-produced HIMARS rocket artillery and Patriot air defense systems, along with their munitions, stands out as the hardest to replace. Moreover, U.S. communications and intelligence support have been crucial to enable Kyiv to track and target Russian troop movements, mitigate Russian air assaults, and strike positions far behind the frontlines.

However, Ukraine's continued reliance on Western military aid will be eased by a European defense industrial base (DIB) that is ramping up, albeit unevenly across weapons systems and inadequately for some capabilities. Defense analyst Fabian Hoffmann notes that while U.S. and European production of interceptors for ballistic missile defense has risen sharply since February 2022, it has not kept pace with Russia's production of ballistic missiles. For cruise missile defense, Hoffmann posits that the outlook is less grim, as European production of interceptors for the German IRIS-T SLM and U.S.-Norwegian National Advanced Surface-to-Air Missile System (NASAMS) is robust, with a manageable gap to Russian missile stockpiles that is expected to narrow significantly in the coming years. Rheinmetall, the German arms manufacturer, has been ramping up its production capacity since 2022 and aims to produce up to 1.5 million 155 mm artillery shells by 2027-effectively contributing the lion's share of the European Commission's objective of achieving an annual production capacity of 2 million 155 mm artillery shells through initiatives such as the Act in Support of Ammunition Production (ASAP) program.

Europe will need to engage the U.S. diplomatically to preserve forms of U.S. assistance that are practically irreplaceable in the short term, while balancing training and force generation against acute labor shortages caused by mobilization, emigration, and economic strain.

The Strategic Imperative

The precarious nature of continued U.S. military support to Kyiv should sharpen minds and stiffen spines among European leaders. As most European leaders have described a sovereign and independent Ukraine as a core national interest, Europe needs a strategy that achieves two objectives. First, in the short term, Ukraine must be able to stabilize its lines to maximize its ability to secure an end to the war on terms that are deemed acceptable to Kyiv. Second, in the longer-term, Ukraine must build a modernized force capable of deterring future Russian aggression. This means Ukraine needs sustained flows of materiel to withstand Russia's war of attrition and to implement a "porcupine strategy" that makes future offensives prohibitively costly. This approach is now explicitly endorsed in the European Commission's "White Paper for European Defence-Readiness 2030." Securing robust long-term commitments from Western partners would send a strong signal to Moscow that time may not be on Russia's side. Underlying these efforts, Europe should anticipate minimal U.S. involvement over the medium to long term.

A Better Path Forward

Taken together, EU-level instruments and national contributions form a sizable but still fragmented ecosystem for supporting Ukraine. While this patchwork has been sufficient to sustain Ukraine through successive phases of the war, it is poorly suited to a future in which U.S. military support is sharply reduced or absent. Under these conditions, Europe should move from crisis response to a more focused strategy-aligning short-term battlefield requirements with long-term force development and European defense priorities. This requires action on four fronts.

Priority 1: Establish Strategic Coherence

Europe should establish strategic coherence in both coordination and production. European provision of aid should become more focused and coherent, resembling the U.S. model of concentrated support for critical systems and enablers. This demands stronger institutional mechanisms and a more rational allocation of industrial responsibilities.

A strengthened role for the EU commissioner for defense and space, working alongside the European Defense Agency (EDA) and the EU military staff, could help align procurement decisions with Ukraine's operational needs while simultaneously reinforcing Europe's own defense posture. Andrius Kubilius, the current EU commissioner for defense and space, has argued for scaling up defense equipment production through cross-border procurement frameworks and has strongly advocated for greater European autonomy in supporting Ukraine.

Joint EU-Ukraine planning forums could be used more systematically to guide investment decisions, particularly as the integration of Ukraine's DIB into Europe becomes unavoidable. Following the first meeting of the EU-Ukraine Task Force on Defence Industrial Cooperation last May, practical steps are needed to launch concrete cooperation initiatives, industrial arrangements, and flagship projects. Kyiv, for its part, will need to leverage its investment capacity, including loan facilities, to cofinance European defense production.

Rather than defaulting to burden sharing centered solely around spending, Europe should distribute production tasks according to the comparative advantage of national industries. A coordinated mapping of Europe's industrial strengths could inform a more rational allocation of production tasks, ensuring that each segment of Ukraine's future force is supported by the most capable suppliers. The goal is not to homogenize national contributions-European states do not all produce the same capabilities-but to ensure efficient specialization.

European firms often under-invest because of uncertainty around future orders, prompting them to prioritize exports outside Europe when they should be reorienting production toward European security needs. The EU commissioner for defense and space, together with agencies such as the EDA, could help mitigate this by steering EU-funded orders toward European manufacturers and providing predictable demand signals.

Priority 2: Hedge Against U.S. Disengagement

Europe should hedge against U.S. reluctance. Ideally, a clear division of labor would be created between the United States and Europe, with the United States providing certain types of weapons, while Europe focuses its efforts elsewhere. However, given limits in U.S. stockpiles and reticence to support Ukraine, Europe needs to hedge-which means spending more and potentially duplicating efforts.

There is currently a debate within Europe over whether to impose strict buy-European clauses for new orders placed for Ukraine. Countries such as Germany argue for flexibility, allowing Ukraine to purchase critical weapons from the United States, such as Patriot missile systems. Countries such as France advocate for stricter buy-European clauses to build up European industry and alternatives, such as the French-Italian SAMP-T air and missile defense system.

Europe should adopt a dual-track approach. For urgent capability gaps where no European alternative exists, or delivery timelines are critical, European funding should support U.S. procurement. For capabilities where European alternatives exist or can be developed within reasonable timeframes, Europe should prioritize its own industrial base. This is not simply due to parochial national interests. Rather, Europe cannot rely on U.S. supply chains it does not control or strategic priorities that may increasingly diverge from its own. The Pentagon has made clear that ensuring adequate stockpiles for the U.S. military is its priority and that the U.S. DIB is currently overstretched and unable to meet demand. As Under Secretary of Defense for Policy Elbridge Colby said in conversation with the European Council on Foreign Relations at the Munich Security Conference, "the fundamental interest the United States has is in allies that are doing more for their own security. If you are going to be spending 3.5 percent on defense, we understand that you are going to indigenize a large fraction," and that the Trump administration recognizes that some large European fiscal expenditures will flow through the European Union.

Europe should certainly support funding to keep critical U.S. weapons flowing in the near term, through mechanisms such as NATO's Prioritized Ukraine Requirements List (PURL) mechanism, which has supplied around 75 percent of all missiles for Ukraine's Patriot batteries and 90 percent of the missiles used in other air defense systems since its inception in 2025. However, it also needs investments in European industries to hedge against a U.S. cut-off over the medium to long term.

Priority 3: Define Ukraine's Future Force

Europe should articulate a credible vision for Ukraine's long-term deterrence. If U.S. involvement remains limited, Europe will need to support what is sometimes described as an "Israel Minus" model: a Ukrainian force capable of independent deterrence without a formal alliance guarantee.

Concretely, this will require:

• layered air defenses capable of mitigating Russian missile and drone strikes;
• long-range strike capabilities to both hold Russian military assets at risk and conduct counter-industry targeting to preempt Russian missiles at the industrial base;
• substantial munitions stockpiles measured in months and years, not weeks;
• robust defensive positions along any future line of control;
• a professional and modernized force capable of combined arms operations; and
• a modern air force, including a substantial number of fighter jets with trained pilots.

Building this force from the base of Ukraine's current battle-tested but weary armed forces will take years and require sustained European commitment. As the Ukrainian armed forces evolve from a mass-mobilized force toward a more professional military operating advanced, high-performance systems, bilateral procurement and European parallel efforts should reflect this trajectory. The priorities outlined above provide the foundation for achieving it.

Priority 4: Secure Long-Term Financing

Stable long-term financing remains the lifeblood of Ukraine's defense planning efforts. European leaders broke a long-held taboo regarding issuing joint debt by agreeing to a loan that supports the Ukrainian state and military through 2027 at the December 2025 European Council summit. The loan will be financed through common EU borrowing from capital markets and guaranteed by the "headroom" of the European Union's long-term budget, while debt-servicing costs will be covered by the bloc's annual budgets. While the loan is currently held up by Hungary's last-minute attempt to block the loan, European Union leaders have been adamant that the funds would go through "one way or the other."

Whether European leaders continue leaning on joint debt or a "reparation loan" backed by frozen Russian assets, they must decide whether to fund off-the-shelf systems, many from the United States, or strengthen the European DIB. Given that European governments bear most legal and financial risk, prioritizing European industry is compelling, and the scale of resources may allow both urgent Ukrainian needs and long-term European industrial expansion to be met. These options can be sequenced or combined to ensure timely disbursements, allowing Europe to address Ukraine's urgent needs while supporting long-term industrial and strategic objectives.

Conclusion

Europe's security architecture is being fundamentally rewritten. As the United States steps back, Europe faces a choice: It can shape this transition by assuming strategic leadership for Ukraine's defense, or it can be shaped by events as Russian aggression continues unchecked. The four priorities outlined here-strategic coherence, hedging against U.S. disengagement, defining Ukraine's future force, and securing long-term financing-provide a roadmap for European action. The window for decisive action remains open, but it will not stay open indefinitely.

Astrid Chevreuil is a visiting fellow in the Europe, Russia, and Eurasia Program at the Center for Strategic and International Studies (CSIS) in Washington, D.C. Otto Svendsen is an associate fellow with the Europe, Russia, and Eurasia Program at CSIS. Max Bergmann is the director of the Europe, Russia, and Eurasia Program and the Stuart Center in Euro-Atlantic and Northern European Studies at CSIS.

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