Russian appears to have raised the scale of hostilities as the US has become distracted with the Israel-Iran war.
Russia and Ukraine have swapped drone strikes, with at least three people reportedly killed by Moscow near the shared border.
Strikes were reported overnight on Tuesday in several areas of Ukraine, as well as in Moscow.
The attacks are the latest in a series of intensifying hostilities as the efforts of the United States to broker a ceasefire have stalled, with Russia appearing eager to take advantage, as global attention is dominated by the war between Israel and Iran.
A Russian drone attack on a village in Sumy killed an eight-year-old boy and two adults, and injured another three people, the military administration of the region said.
