Ukrainian soldiers say Russian drones are dropping tear gas on the front lines, choking troops and starting fires in the trenches

• Ukrainian troops recount horrifying experiences with tear gas on the battlefield. 
• They told CNN Russian drones were dropping the chemical agent in trenches. 
• The resulting injuries and deaths were compounded by trench fires and panic.

Ukrainian soldiers battling in front-line trenches say they are facing a terrifying threat from Russian drones: CS gas, also known as tear gas, leaving troops fighting for breath as fires start around them.