Defence figures suggest heavy use of long-range monitoring could reduce need for soldiers on the frontline with Russia

Britain believes that a European-led security guarantee to Ukraine could be provided with considerably fewer troops than the 100,000 to 150,000 called for by President Volodymyr Zelenskyy last week in the event of a peace agreement.

A European-led assurance force for Ukraine would not necessarily involve large numbers stationed on the frontline, defence sources indicated on Tuesday, and could therefore be in the region of a few tens of thousands strong – or even less.