Shovels in hand and helmets on heads, Ukrainian soldiers jump out of a military truck and prepare to dig a trench near Bakhmut, in the conflict-hit east of the country. The soldiers on the first digging duty put their rifles in the grass and line up along the designated stretch of ground. The others stand slightly back. But the trench-diggers don't even have time to start before the shrill sound of a rocket ripped through the air before falling and exploding less than 50 metres away.