A Canadian who was injured while fighting for Ukraine is going through rehabilitation in Kyiv after suffering third-degree burns to his leg as a result of a drone attack.

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.

The attack mostly targeted western regions of the country, the air force said, where much of the military aid provided by Ukraine's Western allies is believed to be delivered and stored.