Russia launched 72 drones and one ballistic missile into Ukraine overnight into Sunday, the air force in Kyiv said.

Many of the drones aren’t particularly fast or high-tech, but they are cheap enough for the Kremlin to launch more than 700 in one night, in an effort to overwhelm Ukraine’s air defenses. Here’s what we know.

This month’s summits between America, Russia and Europe haves produced no concrete agreements on ending Ukraine’s war. On land, Ukrainian forces are limiting Russian advances on the eastern front to a slow, bloody crawl. At sea too, it is up to Ukraine’s drones, missiles and small boats to keep the Russians out.