The first cluster bomb used operationally was the
German SD-2 or
Sprengbombe Dickwandig 2 kg, commonly referred to as the
Butterfly Bomb. It was used during the
Second World War to attack both civilian and military targets. The technology was developed independently by the
United States of America,
Russia and
Italy (see
Thermos Bomb). Cluster bombs are now standard air-dropped munitions for most nations, in a wide variety of types.
Artillery shells that employ similar principles have existed for decades. They are typically referred to as
ICM (
Improved Conventional Munitions) shells. The US military slang terms for them are "firecracker" or "popcorn" shells, for the many small explosions they cause in the target area.