Europe Can Flex Its Military Muscle to Protect Postwar Ukraine

NATO membership is the only true deterrent against Russian aggression—and bringing Ukraine into the alliance is the only real option for Ukraine and for wider European security. Yet, as the NATO Vilnius summit confirmed, key allies including the United States and Germany are not ready to commit, so this is off the table, at least in the short term.

By removing the Membership Action Plan requirement, the summit communiqué confirmed that any decision on a future alliance will be political, not technocratic. But with no defined criteria for entry, Ukraine’s fate is at the whim of allies. This is, however, also a major opportunity. If political obstacles can be properly addressed and allies persuaded of the merits of enlargement, Ukraine will be able to join.

In the meantime, however, willing European states need an interim solution for the period after the cessation of violence in Ukraine. Counterintuitively, formalizing and announcing such a solution as soon as possible—while the war is still raging—could potentially shorten the conflict. Though Russia would have an incentive to prolong the fighting to avoid the new arrangement coming into effect, the Kremlin’s theory of victory is based on outlasting Western support for Ukraine. A clear interim security commitment would show this to be futile.

To be effective, any such solution needs to fit multiple criteria. It needs to deter Russia from attempting a repeat attack, thus protecting Ukrainians and underwriting the investment needed for their country’s recovery. Second, it needs to bolster European security more broadly to give allies greater incentive to stick to it. And third, it needs to facilitate Ukraine’s entry into NATO—rather than being an alternative to it—by addressing the obstacles that lie in Kyiv’s path.

Those obstacles are political. To be sure, more and more allies have come around to the view that getting Ukraine into NATO is necessary to avoid creating again a dangerous gray zone in the medium term. France is a high-profile recent convert, and all allies reaffirmed their commitment to Ukraine joining the alliance in principle. In practice, however, there is reluctance in key alliance capitals including Washington and Berlin. Both ostensibly want to avoid escalation or getting entangled in a direct conflict with Russia.

Yet Ukraine’s alliance membership runs no such risk. Senior alliance figures have confirmed that NATO believes it has effectively deterred Russia. As a result, NATO allies have repeatedly crossed Moscow’s supposed red lines by supplying Ukraine with heavy weapons, without suffering direct reprisals.

But one genuine problem, from Washington’s perspective, is the relatively light contribution of European allies to their own collective security, despite increases in defense spending in countries like Germany. In light of America’s responsibilities in the Indo-Pacific, the Biden administration is understandably wary of taking the burden of an additional defense commitment—to Ukraine—that, even though Europeans are more directly affected, would fall mainly on the United States.

Breaking this impasse requires an interim solution that can overcome these obstacles. Of all the proposals on the table, only enlarging the Joint Expeditionary Force (JEF) mini-alliance fits the bill, as it would upgrade European defense in the long run while providing an immediately credible security offer to Ukraine.

The JEF was established in 2014 as a U.K.-led NATO framework nation initiative: a group of allies clustered around and working closely together with a large NATO power. It quickly established a reputation for being fast, flexible, and capable and grew beyond its initial power projection mission into more generally ensuring mutual security between its members. It brings together the formidable capabilities of the United Kingdom, the Baltic States, the Netherlands, and the Nordic countries—and has experience of combining NATO and non-NATO members (previously Finland and still Sweden).

Many JEF members—and Poland—strongly support Ukraine’s NATO membership, and several were among the states pushing for stronger language in the Vilnius communiqué. This makes it easier to imagine the group extending an all-important mutual defense offer from the member states to Kyiv. The enlarged JEF would be anchored by the U.K., and its members wield impressive collective air power. Combining this with Poland and Ukraine’s large, capable ground forces, the latter of which are battle-hardened, would make it a credible deterrent force.

The JEF’s modus operandi of conducting frequent joint training exercises and maneuvers would see troops from the involved states in Ukraine, which would act as a “tripwire” deterrent to Russian aggression. And the willingness seems to be there. As British Defense Secretary Ben Wallace said in Vilnius, “You could expect more British troops in Ukraine after this conflict than you did before.”

This coalition of the willing would have a significant stability advantage over any bilateral security pact. Protecting Ukraine as a coalition would not only share the cost of enhanced deterrence between allies, which is important given the budgetary constraints many allies face. It would also make security provision less vulnerable to fluctuations in an individual guarantor’s domestic politics or geopolitical outlook. The enlarged JEF’s alliance-like character would provide a collective spine-stiffening effect that would keep Europe safe and help Ukraine attract the investment it needs to recover.

Crucially, enlarging the JEF would provide a far more credible deterrent than the “hedgehog” option of merely arming Ukraine. This strategy of aiding Kyiv in a “bristling” defense is, unfortunately, what key allies and their G-7 partner, Japan, are pursuing via a declaration that did not offer a mutual defense pact. Instead, alongside commitments to provide arms to Ukraine, they gave vague promises of swift consultation in the event of another Russian attack.

This is unlikely to deter Russia or reassure Ukrainians who have the failure of the 1994 Budapest Memorandum in mind and do not see such offers as meaningful security guarantees. Bundling them together in a multilateral framework does little to alleviate fears that it will be insufficient to deter Russia and would give Kyiv an incentive to seek nuclear weapons of its own—having given up its arsenal for the faulty assurances provided in Budapest.

Another advantage of extending the JEF is that it would go beyond the morally questionable position of delegating the fighting and dying in the name of democracy to Ukrainians. Showing allies a willingness to stand up to authoritarian aggression in the long term would further improve their own deterrence, hurt Russian morale today, and have other positive strategic effects.

Binding themselves to Ukraine would give JEF members greater input over its posture and capability development. It would reduce the risk of Kyiv seeking its own nuclear deterrent (the crucial missing part of the so-called Israel option that some propose). Moreover, it does not deal another blow to Ukrainians who have been rejected repeatedly by Western states—a lose-lose approach with tragic consequences.

For European NATO states, this is not only right, but smart. As Henry Kissinger recently argued, an aggrieved Ukraine, legitimately angry with Russia, feeling rejected by the West, and armed to the teeth may not make for the most docile neighbor—or for a stable and secure Europe. Extending the JEF would have the opposite effect.

Yet European allies should think bigger still. Inviting France to join the JEF would capitalize on Paris’s conversion to NATO membership for Ukraine and serve its need to build trust in Central and Eastern Europe. This would harness (and potentially lock in) the recent constructive turn in British-French relations and the desire to find a role for their existing bilateral Combined Joint Expeditionary Force. France would gain from U.K. credibility in Central and Eastern Europe, while London would benefit from sharing the burden of future capability investment with another major—and nuclear-armed—military power.

Poland is keen to work closely with the U.K., and its impressive military capability development would bring even greater value if it were more closely coordinated with major allies. Creating an effective, NATO-based framework for this purpose that brings together Europe’s major powers is in all their interests. Other allies that have strongly supported Ukraine, such as Tallinn Pledge signatories Czech Republic and Slovakia and naval power Italy, could also be included if willing.

Such a Joint European Defense Initiative (JEDI) could form the basis of a genuine European pillar of NATO. If Ukraine, Poland, and France could agree on such a step with the JEF members, it would be the push Europeans need to take the lead on their own security, as they would need to keep enhancing their capabilities to meet their responsibilities. The JEDI would also provide a useful framework for Europeans to coordinate their defense planning and procurement as well as give them more say in their security.

It would thus offer credible deterrence and better burden sharing without undermining NATO or distancing from the United States. It would also be a moment of truth for Germany, which would have to decide whether or not to join the initiative, sending a clear signal about whether it is ready to live up to its self-declared “special responsibility” for European security.

Unlike NATO, the JEDI could quickly admit Ukraine without a lengthy ratification process—or the risk of vetoes—and so could be operational at the moment hostilities cease. By addressing U.S. concerns and boosting European deterrence, it would also allow for Ukraine to be invited to join the NATO at that time, while recognizing that it would only become a member once the full process had been completed.

European allies that wanted more for Ukraine should channel their disappointment constructively. They can seize the moment and commit to extending the JEF to Ukraine and Poland together with mutual defense obligations when hostilities cease—and offer a way forward to something more.