The Prospects for a Ukrainian Stabilisation Force

Thursday 7 January 2026

Yesterday’s announcement that the United Kingdom and France have agreed in principle to contribute troops to a Ukrainian stabilisation force, contingent upon the conclusion of a peace agreement between Ukraine and Russia, marks a notable development in the evolving architecture of European security. The agreement, reached in Paris during a meeting of a self-described coalition of the willing, reflects a growing recognition in European capitals that the sustainability of any future peace in Ukraine will depend not only upon diplomatic texts but upon credible enforcement and reassurance mechanisms on the ground.

The commitment was formalised in a trilateral declaration of intent signed by the British Prime Minister, Keir Starmer, the French President, Emmanuel Macron and the Ukrainian President, Volodymyr Zelenskyy. While the declaration stops short of operational detail, its political significance should not be understated. It represents one of the clearest signals to date that leading European military powers are prepared to place uniformed personnel on Ukrainian soil in support of a post-war settlement.

Under the terms outlined publicly, British and French forces would deploy only following the conclusion of a peace agreement or comprehensive ceasefire. Their mission would not be combat operations against Russian forces, but rather stabilisation, reassurance and support. This would include assisting Ukraine in maintaining internal security, safeguarding critical infrastructure, supporting the regeneration of Ukrainian military capacity in peacetime conditions and deterring renewed aggression through an international presence that raises the political and military cost of violation.

Central to the concept is the establishment of secure military hubs across Ukrainian territory. These facilities would function as logistics centres, training bases and coordination nodes rather than forward combat positions. They would enable cooperation with Ukrainian forces, provide secure storage for equipment and offer a visible symbol of international commitment to Ukraine’s post-war security. The intention is to prepare the legal and institutional framework for such deployments in advance, so that the force could be activated rapidly once a political settlement is reached.

Strategically this marks an evolution in Western engagement. Since 2022 support for Ukraine has been extensive but indirect, focused upon arms transfers, intelligence sharing, training outside Ukrainian territory and financial assistance. The willingness of London and Paris to contemplate a stabilisation deployment inside Ukraine suggests a judgement that any peace unsupported by physical guarantees would be dangerously fragile. It also reflects concern that a security vacuum following a ceasefire could invite renewed coercion or gradual destabilisation by Russia.

Yet the declaration also raises an unavoidable practical question: how many troops would be required to make such a stabilisation force effective rather than merely symbolic?

Ukraine’s scale immediately complicates the answer. She is a vast country, with dense infrastructure, large urban centres and a long militarised frontier that would likely persist in some form even after a peace agreement. A stabilisation force could not be expected to police every kilometre of a ceasefire line, but even a limited mandate focused on key nodes would demand substantial manpower.

Historical comparisons are sobering. NATO’s deployment to Kosovo at the end of the 1990s involved approximately 50,000 troops to stabilise a territory a fraction of Ukraine’s size. Bosnia and Herzegovina required a similar level of international military presence in its immediate post-war phase. Even UN peacekeeping missions often regarded as modest, such as UNIFIL in southern Lebanon, operate with around 10,000 troops in far less complex strategic environments. None of these precedents involved a defeated or constrained great power with Russia’s military depth positioned immediately across the line of contact.

If the proposed stabilisation mission were confined to protecting major logistics hubs, ports, airfields, training centres and selected urban areas, a force of at least 20,000 to 30,000 troops would likely be required to achieve basic credibility. Anything smaller would struggle to provide persistent coverage, respond to incidents or sustain rotations without exhaustion. Should the mandate expand to include monitoring of ceasefire lines or demilitarised zones, the required numbers would increase significantly.

For the United Kingdom and France this would represent a demanding but not inconceivable commitment. Both maintain professional expeditionary forces with experience in sustained overseas operations, but both also face manpower constraints and competing global obligations. A British contribution in the order of 5,000 to 10,000 troops (as has been discussed), matched by a similar French deployment, would be plausible only if embedded within a wider multinational framework involving other European states. Without such reinforcement, an exclusively Anglo-French force would risk being politically resonant but operationally thin.

Numbers alone, however, would not determine success. A credible stabilisation force would require a full spectrum of capabilities: engineers, logistics units, medical services, intelligence assets, air defence, communications and rapid-reaction elements capable of responding quickly to violations or provocations. Russia’s conduct throughout the war has demonstrated a preference for probing below clear thresholds, using ambiguity, pressure and incremental escalation. Deterrence in such an environment depends as much upon responsiveness and resilience as upon headcount.

The uncertainty surrounding Russian acceptance of any Western troop presence remains acute. Moscow has consistently opposed the deployment of NATO or NATO-aligned forces in Ukraine, even in a post-conflict context. Whether such objections could be reconciled with a peace settlement, or whether the stabilisation force would itself become a focal point of tension, remains unresolved. For this reason the agreement announced yesterday remains prospective rather than operational.

Nevertheless its significance is clear. By committing in advance to the possibility of deploying troops, London and Paris are signalling that peace in Ukraine cannot be reduced to lines on a map or signatures on paper. If realised at sufficient scale and with sufficient endurance, a stabilisation force could play a decisive role in deterring renewed war and anchoring Ukraine’s sovereignty within a new European security settlement. If under-resourced, by contrast, it would risk offering reassurance without protection, and symbolism without security. For Ukraine, the difference between those outcomes is existential.

In short: the number of troops committed in yesterday's agreement is probably not enough if the goal is to police a frontline ceasefire, and other countries will have to make commitments in due course.