Authorities say Russian drones have slammed into two Ukrainian cities, killing at least one person in nighttime attacks.

Moscow’s drone strikes have grown exponentially thanks in part to a deal with Iran to produce its Shahed drones on Russian soil. An attack overnight that focused on Kyiv killed at least 15.

The assault continued Moscow’s stepped-up drone and missile attacks, which have been ratcheting up for months with nightly bombardments on regions and cities in Ukraine.