Meaningful Security Guarantees for Ukraine
01 December 2025
Benjamin Stokes
Security guarantees for Ukraine have been widely debated, especially over the last year since the change of administration in the United States. I was very grateful to have the opportunity to explore some of the key issues around this subject at the Oxford Ukraine Hub in September 2025. In this blog post, which builds from those discussions, I highlight what might make security guarantees meaningful and address the significance of such guarantees in the context of Russia's ongoing brutal war against Ukraine.
Meaningfulness of Guarantees
There are two basic ways, I want to suggest, in which security guarantees may be considered meaningful and hence have potential value.
The first-order test concerns whether the guarantees-or the system of guarantees-could be sufficient, or plausibly sufficient, on their own to prevent the (resumption of) a full-scale attack by Russia. The NATO alliance is often understood in these terms.
The second way in which security guarantees may be meaningful involves systems that have a real dissuasive effect on the adversary, but can only plausibly be one factor among several in achieving successful deterrence. In such cases, deterrence depends on additional, external factors for actual success. In what follows, I focus on systems of the first kind: those that aspire to be sufficient in themselves to deliver successful deterrence.
Capability
Only a guarantee system that involves the United States can, at least for now, deliver meaningful security in this first-order sense, whether in Ukraine or elsewhere along the eastern frontier of Europe. The European powers alone currently cannot plausibly deliver a strong, credible deterrence effect against the Russian state in this theatre. However, that does not mean that this European-led capability cannot be built. Doing so would require, as Henrik Larson recently has categorised it, significant developments in four major areas:
the capability to concentrate conventional armed force on the eastern frontier and credibly reinforce them;
the provision of so-called 'strategic awareness' from intelligence and satellite systems;
a credible and balanced tactical and strategic nuclear stance vis-a-vis Russia; and
political leadership and decision-making structures that can act and signal with credibility.
Discussion of the first three areas, and the technical capabilities they involve, is already relatively well developed, if often highly complex. I therefore focus on the fourth. This is especially important because, in Europe, political structures and leadership cannot be organised in a way analogous to the United States: there will be no second 'Oval Office in Brussels' and no single President or Commander in Chief of Europe. In other words, there can be no singular, centralised site of agency for the region.
The European Union institutions have an important role to play, particularly in financial coordination and fostering societal resilience, but by design, they cannot lead the political direction of defence. That remains the prerogative of sovereign states. Only effective inter-state cooperation - between allied sovereign democracies - can therefore plausibly deliver effective deterrence. This is one reason why it makes sense to work on this problem within NATO-by developing its 'European pillar'-since NATO has a proven record of enabling such state-to-state cooperation.
This does not preclude additional formats for sovereign state cooperation, such as an expanded Weimar+ format in which the European Union's institutions also participate. Nor does it rule out a denser web of strong bilateral relations between key European countries, including Ukraine. The core question is whether Europe's sovereign democracies can harness their combined strength to successfully deter Russia. This inter-state cooperation is not only an international priority; it is also tightly bound up with domestic politics and democratic resilience at home. Viewed this way, Ukraine's participation in this system is essential-not only as a recipient of guarantees, but, in the medium term, as a partner in that shared deterrence effort.
The War Continues
The Russian state failed in its initial bid in early 2022 to impose regime change in Kyiv and, through that, to end Ukraine's participation as a sovereign actor in Europe's societal, economic and security space. This failure-which stemmed from a profound misreading of the will, courage, and capability of Ukrainians to resist the imposition of Putinite tyranny in their country-has not, however, convinced the Kremlin to revise its goals. The war therefore continues.
Any discussion of security guarantees must be grounded in this reality; for now, and for the foreseeable future, the only end to the fighting that the Kremlin appears willing to accept is one that leaves Ukraine largely defenseless against future attack. Such an outcome would be no genuine 'peace' at all and would make the eventual imposition of Putinite tyranny in Ukraine all but inevitable, and likely swift. It is vital to recognise, therefore, that a core objective of the Russian state is precisely to prevent meaningful guarantees of Ukraine's sovereignty-and that it pursues this aim primarily by continuing the war.
The only way to change this equation is to increase, over time, the costs and risks that the Russian state associates with continuing the war above those they perceive from Ukraine becoming party to meaningful security guarantees, allowing for ongoing sovereign Ukrainian participation in European affairs. This is a tall order. How best to achieve it is arguably the most pressing political question in Europe today, and it is clear that Russian fossil fuel energy export revenues lie at the heart of the problem.
Meaningful security guarantees are therefore not at all a solution to the current war but an outcome only made possible by the eventual success of Ukrainian self-defense and sustained pressure on Russia. That success must come first. When it does, Europeans must be ready to lead in guaranteeing the new peace.