Russia launched a rare drone and missile attack on western Ukraine overnight, officials said Thursday, striking targets including an American-owned electronics plant and injecting further uncertainty into the U.

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.

Russia launched a massive overnight assault on Ukraine, firing 614 projectiles in what marks the most extensive aerial strike in three weeks. The Ukrainian Air Force reported intercepting or electronically jamming 546 drones and decoys, along with 31 missiles. Despite these efforts, strikes landed in 11 locations, including in Western Ukraine.