Europe’s discussion of a multinational military presence in Ukraine has intensified after a meeting of the Coalition of the Willing in Paris on 6 January produced a “Paris Declaration” on security guarantees for Ukraine.

Issued by France, the declaration sketches a post-ceasefire architecture that includes a monitoring and verification mechanism and the creation of a “multinational reassurance force” under French and British command.

Moscow has rejected the concept. Russian officials criticised the Paris document and warned that any foreign troops deployed in Ukraine would be treated as legitimate targets. Russia has not signalled readiness to accept a settlement that incorporates the kind of external security guarantees envisaged by Kyiv’s partners, leaving European planning dependent on political conditions that are not yet visible.

The feasibility of any European contingent turns on a basic mismatch between political intent and available forces. Britain’s deployable land contribution would likely amount to no more than two brigades — roughly 7,500 troops — while France might be able to field around 15,000, with limited scope to expand. In this assessment, “a few tens of thousands” would not be decisive if the mission were framed as conventional peacekeeping or control of a ceasefire line. A monitoring and enforcement role along a long frontage would require far larger numbers and a strong reinforcement plan.

Recent reporting has pointed to similarly modest force levels, at least at the outset. UK has earmarked £200 million to prepare for a possible deployment, with spending directed at upgrading vehicles, communications and counter-drone measures so British forces could deploy if a ceasefire were agreed. In France, Le Monde has reported that President Emmanuel Macron discussed a French contribution of several thousand troops, presented domestically as support for the Ukrainian armed forces rather than a front-line combat force.

The likely role of any European contingent would depend on how the mission is designed. The Paris Declaration and related analysis point to a reassurance force intended to strengthen Ukraine’s security after a ceasefire, rather than substitute for Ukrainian units on the front line. Yet at any plausible scale, European troops would be most effective in support roles that could begin immediately, not only after a political agreement: expanding and protecting training facilities; securing critical sites and transport hubs; supporting airfields and flight operations; strengthening logistics; and enabling defence-industrial activity, including co-operation on weapons production.

Such tasks would keep European troops away from the main line of contact while still placing them inside Ukraine. They would also align with how some European reporting has described prospective deployments: a rear-area presence focused on training, protected facilities and support functions, rather than a “tripwire” force intended to hold ground.

Even in this narrower conception, numbers and sustainability remain limiting factors. A small deployed force creates a larger force-generation requirement at home because units must be rested, retrained and replaced. A country able to keep two brigades in theatre needs additional brigades in reserve for rotation and other overseas commitments, which restricts what smaller European armies can sustain over time.

Financing and domestic politics shape the options as much as troop numbers. Germany could be a pivotal financier, even if Berlin remains cautious about deploying its own troops for historical and political reasons. The argument is that, with German funding, British and French leadership, and additional contributions from states that see themselves as directly exposed to Russia, Europe might assemble a force of roughly 60,000 to 80,000 personnel. Even that would likely fall short of what is required for a credible enforcement mission across a country the size of Ukraine, particularly if the aim is to deter or respond to violations without relying on Ukrainian forces.

The United States remains a decisive variable. The Paris meeting included US participation, and Washington backed the concept of security guarantees. At the same time, the deployment of regular US forces appears unlikely. A more plausible American contribution would be expanded advisory and training support and deeper defence-industrial co-operation — a larger technical footprint and joint projects focused on transferring battlefield lessons and strengthening Ukrainian capabilities, rather than establishing US combat units on Ukrainian territory.

For Kyiv, the strategic calculation is whether a European reassurance force would materially strengthen deterrence or function mainly as a marker of long-term commitment. The Paris Declaration points to an effort to connect continued support to a post-ceasefire framework, but Russia’s stated opposition to foreign troops underlines the difficulty of translating a declaration into an operational deployment.