cluster munitions or cluster bombs, air-dropped or ground-launched weapons that open in mid-air and scatter dozens, hundreds, or thousands of smaller submunitions (or bomblets) over a wide area. Such munitions are effective against targets that do not have fixed locations, such as enemy soldiers or vehicles, and also against precise positions, such as airfields and missile sites. Artillery shells that employ principles similar to cluster munitions have existed for decades.

There are a number of types of submunition-based weapons: antipersonnel, which rely on explosive fragmentation to kill troops and destroy unarmored targets; antitank, which utilize shaped-charge warheads to pierce the armor plate of tanks and armored fighting vehicles; incendiary, which are intended to start fires by employing white phosphorus and napalm bomblets; anti-electrical, which interfere with electric power transmission lines by creating short circuits with carbon fiber or aluminum-coated glass fiber bomblets; mine laying, which like land mines do not explode immediately but wait to be triggered by pressure or magnetism; antirunway, which are designed to penetrate concrete before detonating so as to crater and shatter runway surfaces; leaflet dispensing. which drop large quantities of propaganda materials behind enemy lines; and chemical/biological weapons of mass destruction. For humanitarian reasons the last was banned by the Chemical Weapons Convention of 1993, and stockpiles amassed by six nations are being destroyed. Antipersonnel mines deployed by mine-laying cluster munitions are banned under the 1997 Mine Ban Treaty (also known as the Ottawa Convention), which prohibits the production, stockpiling, and use of antipersonnel mines.

Because unexploded bomblets scattered by cluster munitions can remain dormant for years after a conflict ends and then be triggered by a noncombatant (often a child), the Cluster Munition Coalition, the International Committee of the Red Cross, United Nations organizations, other organizations, and many nations began negotiations to produce a treaty banning submunition-based weapons in 2007. A treaty outlawing cluster bombs and giving ratifying nations eight years to destroy such weapons, known as the Oslo Convention, was approved by more than 100 nations in May, 2008, and signed in Dec., 2008; the treaty entered into force in Aug., 2010. Among the nations that did not participate in the conference that adopted the draft were the United States, Russia, China, India, Pakistan, and Israel. A proposal, sponsored by the United States and supported by Russia and China, to regulate cluster munitions as part of the UN Convention on Certain Conventional Weapons was rejected in 2011 by other nations that saw the measure as watering down the Oslo Convention.

cluster bomb: see cluster munitions.