The relative calm in Ukrainian cities far from the country’s battlefields was shattered by two painfully familiar sounds this week: the ominous ring of the air raid sirens, and the eruptions of Russian attacks.

A wave of missiles, rockets and drones has struck dozens of locations across Ukraine since Monday, according to officials, targeting civilian infrastructure in several major cities, including Kyiv, located hundreds of miles from the front lines in the east and south.

The wide bombardment echoed the early days of Russia’s scattershot initial invasion in February, but also underlined that the conflict in Ukraine, which for months appeared to be descending into a slow and painful grind in the Donbas, has erupted once again as winter nears.