Securing Ukraine after the war: what role for Europeans?

The security guarantees that the West provides to Ukraine will be a critical element in the settlement of the war with Russia, which Trump has suggested will take place soon after his inauguration. Although a discussion of how to guarantee Kyiv’s future security might seem premature, Europeans would do well to prepare for the possible cessation of hostilities by producing their own proposals for peace and security on the continent.  

In the current political climate, the most likely form that security guarantees for post-war Ukraine could take is that of a new multilateral collective defence framework, supported jointly by a coalition of European countries, backed by their military presence, and circumscribed to free Ukrainian territory. It would certainly not be without its issues and limitations, but it arguably represents the most realistic option on the table today. 

NATO membership would undoubtedly offer the best collective protection to which Ukraine could aspire after the war. But accession to the alliance is decided by unanimous agreement and so far that has not been forthcoming, nor is it likely to be. Membership of the European Union, although desired on all sides, is unlikely to offer a viable security option in the short term. European treaties include a collective defence clause under Article 42.7 of the Treaty on European Union (TEU). Nevertheless, the Union’s role in terms of collective defence remains modest and carries little military credibility.  

The network of security agreements signed between Ukraine and more than thirty NATO and EU countries over the past few months, following the G7 declaration in Vilnius in 2023, is unlikely to provide a satisfactory solution either. In terms of postwar security guarantees, these bilateral agreements are all essentially consultation pacts, combined with a commitment to helping Ukraine defend itself, for instance through additional arms transfers, should it again be attacked by Russia. They do not amount to fully fledged collective defence commitments, whereby Kyiv’s partners would undertake to defend Ukraine with their own armed forces against future Russian aggression. 

The idea of sending ‘peacekeepers’ to Ukraine after the war was recently floated by German and Italian officials but is unlikely to work. Russia would need to acquiesce to the idea. Moreover, a peacekeeping mission would be operationally unsuited to acting in any large-scale, high-intensity outbreak of hostilities. In brief, this option would ultimately leave Ukraine’s security at the mercy of Moscow, both politically and militarily. 

To do nothing, either by choice or through a failure to reach a common position among Europeans, also presents risks and potential costs. If Ukraine is left to fend for itself once peace returns, the risk of further Russian aggression is high.  

For lack of a better alternative, Europeans must therefore seriously consider the possibility of establishing a new collective defence framework for Ukraine. What might be its guiding principles?  

Firstly, such a framework would have to rely mainly on countries in Europe, as Washington will likely oppose further extending its security responsibilities to the old continent in any shape or form. ‘Europe’ is understood here in its continental sense and not limited to the EU. In particular, the participation of the United Kingdom, as one of Europe’s major diplomatic and military powers, will be critical.  

Secondly, a new collective defence framework for Ukraine would have to be multilateral. Without the direct participation of Washington, Europeans would indeed be faced with an acute collective action problem, insofar as individual European countries would be reluctant to commit to Ukraine’s defence if they were not assured that a sufficient number of partners were doing so as well. 

Thirdly, a new collective defence framework would have to be geographically limited to free Ukrainian territory. It would be necessary to exclude territory currently occupied by Russian forces, to avoid triggering a direct military conflict with Moscow. In addition, the new collective defence commitment would also need to apply to all the parties that have military personnel deployed in the region. European troops deployed in Ukraine would fall outside the geographical scope of NATO’s Article 5 (or, for that matter, that of Article 42.7 TEU). Russia might then be tempted to drive a wedge between European countries by striking the forces of one of them in Ukraine, to test European solidarity. To prevent this, participating European states would have to undertake not only to defend free Ukrainian territory collectively, but also to respond jointly to an armed attack against the forces of any of them stationed there.  

Finally, the new collective defence framework would need to be underpinned by a European military presence. Preliminary discussions have so far focused on the overall format of such a European military presence. No numbers have officially been proposed, but analysts have recently estimated that a coalition of European countries could and should provide five brigades in addition to an air defence component.  

The exact strategic rationale underpinning a European military presence of this scale remains unclear. Would it primarily serve a political function, as a ‘tripwire’ to ensure that all of Kyiv’s protectors would be involved early in a conflict, or would such a presence be designed as a genuine forward defence, capable of warding off another large-scale Russian offensive? An explicit answer to this question is unlikely to be provided, as perspectives on the matter will likely differ not only between Ukraine and its European guarantors, but also among the guarantors themselves. 

In contrast, the distribution of the human, military and budgetary resources that each side will have to contribute will quickly become concrete. The coolness with which Prime Minister Donald Tusk responded to the question of whether Poland had any plans to send troops to Ukraine after the end of hostilities may be an early sign of the tensions to be expected in this regard. It is indeed quite possible that the Polish prime minister was reluctant to say, at least at that stage, that Warsaw is willing to commit troops to Ukraine because he considers that Poland is already bearing a significant share of the burden of Europe’s defence, as the largest frontline country within NATO. 

Just as Europeans have proclaimed over the past three years that nothing about Ukraine should be decided without Ukraine, they should strive to ensure that nothing about Europe’s security should be decided without Europeans. But this cannot simply be a moral principle that they proclaim. It is only by proposing solutions for the security of Ukraine and the wider continent that Europeans will be able to make their way to the negotiating table alongside the United States.