A ceasefire is neither a quick fix nor a satisfactory long-term solution. How a truce is defined and implemented matters. In fact, a rushed or badly designed ceasefire could risk making a permanent solution harder to achieve.
As 2026 began, and Russia’s war on Ukraine entered its fifth year, hopes of an end to the conflict remained unrealized but alive. Despite little significant change in the military position on the ground in 2025, the year saw intermittent efforts to set out a vision of how the war might be ended. These encouraged a perception that a comprehensive settlement remained out of reach for the foreseeable future, but that the prospects of such a settlement might be helped, not dimmed, by an agreed cessation of hot war: a ceasefire.
The US intervention in Iran has, for now, lowered expectations of any great shift in the dynamics of Russia’s war on Ukraine. But the intervention has arguably created a situation where it is now even more important for President Trump to achieve a quick win: what he can describe as an end to the war in Ukraine, even if the result falls far short of that. A Russia–Ukraine ceasefire is an objective that could rapidly regain momentum and urgency.
This research paper, accordingly, examines the extent to which Europe, for the sake of its own security, needs to build yet more substantive agency and investment into its partnership with Ukraine. We underline, drawing on a broad range of precedents, how Russian exploitation of a badly constructed ceasefire can lead to even greater threats to the continent’s security and stability. And we highlight the need for countries across Europe to secure fundamental improvements in their capacity to contain and deter such threats.
Superficially, a ceasefire looks like a pragmatic initiative: resolving a seemingly less difficult objective, while giving time and space for the greater complexities to be addressed with cool heads and purposeful method. But a ceasefire is not ‘the easy bit’. How such an agreement is defined and enforced, and how different actors implement it, matters profoundly. Two essential questions need special attention: how will the ceasefire be made durable? And looking beyond the ceasefire itself, what are its likely longer-term consequences: do these scenarios look desirable, tolerable or unacceptable?
In previous Chatham House research, we have underlined the importance of increased effort to achieve a comprehensive, just and durable solution. This paper neither advocates for nor recommends against a ceasefire as a necessary or desirable precursor to a long-term peace settlement. But the paper recognizes that the idea of a ceasefire as a possible ‘least-bad’ near-term option has emerged against a background of a number of persisting factors:
- Russia’s determination to extinguish Ukraine;
- Ukraine’s determination to defend its independence;
- Europe’s failure to mobilize resources with sufficient speed and substance; and
- The US’s disinterest in European security (now exacerbated by Trump’s anger at many NATO allies’ response on Iran).
Clarity of a ceasefire agreement and effective enforcement are key pillars of any durable deal. If Russia continues a practice of injecting uncertainty into the process in the form of intentionally ambiguous conditions, a ceasefire can be easily undermined. The terms and tools for an effective ceasefire need not be innovative. But they must be thorough and unarguably clear. For example, the range of permitted activities within any zone of separation must be clearly prescribed. In the near term at least, proposals for a ‘free economic zone’ should be dismissed. Such a zone might conceivably have value as a confidence-building measure in the future. But inserting an under-regulated business environment into the middle of a conflict area risks deliberately introducing the sort of ambiguities that could quickly kill a ceasefire.
Effective enforcement of any ceasefire will normally require credible degrees of deterrence and disincentives to be in place. But while the core obligations of a ceasefire agreement will be the same for both parties, their motives for honouring – or violating – these commitments will be different.
For Ukraine, agreement of a ceasefire while significant tracts of its land remain under Russian occupation would represent the reluctant acceptance of the least-bad available option for stopping hostilities. It is a choice that prefers an inherently unsatisfactory cessation of the conflict over the continuation of a war in which the inputs of Ukraine’s supporters have been consistently inadequate to help Ukraine win. The need to avoid being punished by the Trump administration for ‘not wanting peace’ will be an additional incentive for Ukraine to show commitment to a ceasefire. President Volodymyr Zelenskyy’s public commitment to a ceasefire based on the current military position is hardly his ideal first choice. But such a pause would allow focus to turn to building robustness, resilience and defensive capability into Ukraine’s future – and to the crucial question of security guarantees. Against such a backdrop it is hard to argue that there is a need for additional disincentives to deter Ukraine from breaking the ceasefire.
Things look different from Moscow. Russia has become the most sanctioned country in history because it is waging a war of aggression on Ukraine. As President Putin’s repeated assertions of maximalist objectives underline, that aggressive intent persists. It is unlikely to be ended by a ceasefire. That reality, in turn, argues against any proposal to offer Russia sanctions relief as an incentive to agree a ceasefire. The road to a just and durable peace following a ceasefire will be complex. It will not be made easier if significant potential leverage over Russia’s posture and actions continues to be given away too easily (see, for example, the Trump administration’s often-repeated assumption that Ukraine must give up territory, and the US’s rushed acceptance of proposals from Moscow that led to the 28-point plan).
The road to a just and durable peace following a ceasefire will be complex. It will not be made easier if significant potential leverage over Russia’s posture and actions continues to be given away too easily.
It could also be a long road to a comprehensive settlement. Ceasefires can last a long time. They can, as was the case in Korea and Cyprus, lead to a de facto new security environment in which a more fundamental resolution remains out of reach for years. Today’s fractured and deglobalizing world offers no hard basis for confidence that any Ukraine ceasefire agreement reached in the coming year will endure. Nonetheless, the drafters and negotiators of a Russia–Ukraine ceasefire will need to keep firmly in mind not only the provisions that govern the ceasefire itself, but the environment it creates, and the extent to which it leaves the door open for positive change in the future or freezes in place an unsatisfactory outcome.
Even the most meticulously constructed ceasefire will fall well short of a comprehensive solution. The best it can do is to bring about a ‘grey peace’, where the fighting has stopped, but fundamental issues remain unresolved. Under such circumstances, we must assume also that the impulses driving the conflict will remain in motion.
For Ukraine’s future, progress towards joining the EU will need to continue and develop as an essential sustaining dynamic. On Russia’s side – at least as long as Putinism persists – its actions to undermine neighbouring states and recreate a subservient and dependent periphery will continue. Crafting a ceasefire could yet be an opportunity to set in motion the change that will provide for a more stable, cooperative region in the future. But – as the 20-point peace plan put forward by Zelenskyy in December 2025 underlines – this provisional, inherently unsatisfactory ‘grey peace’ will be impossible to sustain if the question of credible security guarantees is not at the heart of European, ideally Euro-Atlantic, strategy.
