IVANIVKA, Ukraine — Olena peered out from her bedroom window to see what looked like her neighbor, a tall man nicknamed Girovka, step out of a car with Russian markings and begin sending flares into the night sky from the side of the road. The next day, Russian tanks and armored vehicles emerged from the woods in a long column, descending on this small village about 60 miles south of the Russian border, along the same road.