Europe's Reassurance Force: Three military options for Ukraine post-ceasefire

As the UK and France push for a European force to secure any future peace deal in Ukraine, new analysis from the International Institute for Strategic Studies (IISS) outlines three possible military options – each with major implications for capability, readiness and risk.

The publication comes ahead of the next meeting of the Coalition of the Willing in Brussels on Thursday.

But what could a military force look like? The IISS has analysed three options.

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Small-Scale Force:

A deployment of around 10,000 troops could be mobilised quickly as it would need the fewest assets and troops.

But that advantage could be outweighed by being a symbolic rather than credible combat force.

It would have minimal air and naval support and would still be dependent on US intelligence, surveillance and reconnaissance (ISR) assets.

Medium-Scale Force:

A divisional-sized force of around 25,000 troops would take longer to deploy, but offer a stronger deterrent.

It could counter a similarly sized Russian incursion and defend itself more effectively than a brigade.

However, the IISS research suggests it would have gaps in some areas, including air defence.

Large-Scale force

A full-scale force of 60,000-plus troops supported by significant air and maritime components would provide the maximum deterrent effect.

But sustaining it would, according to the IISS, stretch Europe's military to the limit.

The report highlights potential shortages in long-range artillery, ammunition, logistics and medical support – especially in the absence of US support.

Ben Barry, one of the authors, says size is important - but so is location.

"If deterrence is the top priority, then having boots on the ground is a way to do it," he said, suggesting troops could be split between Ukraine and neighbouring Eastern European countries.

The paper also emphasises the need for a US backstop, arguing that American intelligence would be crucial for all three options.

It warns that without President Trump's support, European forces would struggle to detect Russian build-ups and respond effectively.