Over the last five days of May, Ruslan, an English teacher in a Russian town near the Ukrainian border, heard the distinct sound of a multiple rocket launcher strike for the first time. Shelling would begin around 3 a.m., sometimes shaking his house, and continue through the morning.

He had heard the thud of explosions in distant villages in the past, he said, and in October, shelling damaged a nearby shopping mall. But nothing like this.

"Everything changed,” he said.