Soldiers scramble through trenches under a haze of yellow smoke, machine gunfire booms across the fields, invisible drones buzz overhead and voices scream in Ukrainian "Watch out!"

The French military force is training a whole new brigade of several thousand Ukrainian troops who will be joining the fight against Russia’s invasion armed with France-supplied tanks, artillery canons and other heavy weaponry.

Around 2,000 Ukrainian soldiers are training in France's eastern Marne region, where German and French armies battled each other during World War I.