MARINKA, Ukraine — It was wet and freezing cold inside: Bare earth floor with a dozen mattresses scattered around it, unfinished tea in an aluminum mug, a few pieces of bread on a plate on top of a dark green wooden box with army ammunition; a bunch of muddy rubber boots by a pile of bags with sand, a soldier’s jacket drying on a nail in dim light. It could be a scene of the soldiers’ life in World War I, but it is modern times.