Ukrainian soldiers crawl on their bellies at the edge of a forest to support comrades assaulting an enemy trench — a life-size exercise in a French military camp training them for real fighting against Russian invaders.

This Ukrainian unit is finishing a four-week course on infantry combat, with their numbers, identities and location kept secret for security reasons.

With an average age of between 35 and 40, the recruits include called-up reservists, newly mobilized civilians and volunteers. Most have never seen battle.