What Are Cluster Munitions and How Do They Work?

What Are Cluster Munitions and How Do They Work?

Cluster munitions or cluster bombs are a controversial category of explosive weapons because their wide area of effect readily renders them as inherently indiscriminate weapons unsuitable for precision targeting or for distinguishing between combatants and civilians.

The United States used these weapons in the Vietnam War, particularly as part of airstrikes targeting combatants in Vietnam, Laos, and Cambodia. Russia has been accused of using these weapons in the recent Russia-Ukraine conflict.

Note that cluster bombs are part of the firepower of the Russian Armed Forces. Other known users include the United Kingdom and Israel, as well as non-state armed factions such as the Islamic State of Iraq and the Levant and the separatist groups in Donbas.

But the establishment of the Cluster Munition Coalition in 2003 and the introduction of the Convention on Cluster Munitions in 2008 marked a globalized effort among state actors to prohibit these weapons  due to their devastating effects

How Cluster Munitions Work: Design and Operational Mechanism

To understand better, a particular cluster bomb releases smaller submunitions or ejects explosive bomblets before hitting the ground. These submunitions would land across a wide area before detonating to produce a series of explosions or multiple explosions at once.

A basic bomb following this design and operational mechanism is typically made of a hollow shell. The shell contains submunitions or bomblets that number between two to 2000 or even more depending on the design and intent of usage.

The primary shell is fundamentally both a container and a dispenser of smaller munitions. Firing or dropping this weapon would essentially be tantamount to producing a rain of smaller munitions or explosives that can cover a wide area.

One of the first known operational versions of cluster munitions was the Butterfly Bomb or the Sprengbombe Dickwandig 2 KG that was developed and used by Germany against several targets in the United Kingdom during the Second World War.

The Butterfly Bomb consisted of a main container that housed bomblets called the Eggs of the Devil. The main container releases these smaller munitions in the air to produce ground explosions. The uses of cluster munitions have evolved since then.

Delivery and Deployment: Known Types and Uses of This Weapon

A cluster bomb can be fired from a land-based or ground-based launcher or dropped from a combat or bomber aircraft. Some versions use parachutes to slow down the descent of the bombs and give them ample time to initiate the first stage charge.

Fundamentally, the two types of cluster munitions are based on delivery. These are ground-based munitions and air-based munitions. However, they have also been categorized based on their intended use or the intended effect and tactical merit.

Below are the following types and uses of cluster munitions:

• Incendiary Cluster Bombs: These bombs are intended to start fires to clear a particular territory such as a forested area or destroy equipment. Extensive usage can create firestorms and conflagrations. Some variants contain and deliver submunitions or bomblets based on thermobaric weapons technology.

• Anti-Personnel: Cluster bombs designed for anti-personnel purposes are based on explosive fragmentation to deliver fatal blows to troops and destroy unarmored or unreinforced inanimate objects. Some designs take into consideration both incendiary and anti-personnel purposes for maximum impact.

• Anti-Tank and Anti-Armor: This type of cluster munition typically has either a shape charge warhead or explosively formed projectile to pierce through tanks and armored combat vehicles. Some designs have guided submunitions for precision targeting while others produce shaped-charged and fragmentation effects to simplify the tactical use of bombs and increase battlefield damage.

• Laying of Mines: A cluster munition can also be used to lay mines. The primary shell contains either or a combination of anti-tank and anti-personnel mines as submunitions. These submunitions do not detonate upon hitting the ground but function like conventional land mines. Deploying mine-laying cluster munitions effectively create landmines faster than conventional mine-laying practices.

• Chemical and Biological Weapons Delivery: Both the U.S and Soviet Union used the operational mechanism behind cluster weaponry to deploy and deliver chemical or biological weapons toward their targets during the 1950s and 1960s. These bombs fundamentally contain smaller chemical-releasing devices as submunitions or bomblets that release microbiological agents.

• Anti-Electrical Cluster Munition: A conventional anti-electrical cluster munition has a primary shell that functions as a container and dispenser of smaller submunitions that can generate small explosive electrical charges that can disrupt or damage electric power transmission systems or jam electronic communication systems.

• Leaflet Dispensing: A cluster munition can also be used to drop large quantities of propaganda leaflets or other informative materials enclosed in bomblets. These bomblets ensure that the material would land on the intended target area without being dispersed by air currents or strong wind. The LBU-30 is a prime example.

International Opinions: Dangers and Criticisms of Cluster Weapons

Cluster munitions designed as explosive weapons have been criticized by several actors within the international community. The Convention of Cluster Munitions was drafted in March 2008 and signed in December 2008 by 110 state parties.

Some signatories include European countries such as the United Kingdom, France, and Germany, Asian countries such as Japan and the Philippines, Middle East countries including Afghanistan and Iraq, and South American countries such as Colombia and Cuba.

This international treaty prevents parties from producing, stockpiling, transferring, and using cluster bombs. It also provides a framework for victim assistance, stockpile destruction, clearance of contaminated sites, and risk reduction education.

Several countries opposed this treaty. These include China, Russia, the United States, India, Israel, Pakistan, and Brazil. The American government acknowledges the humanitarian concerns attached to the use of cluster weapons.

However, for the Americans, the proper venue for discussing the status of cluster munitions is through a forum under the Convention on Certain Conventional Weapons. The U.S. government also noted that guided submunitions reduce indiscriminate targeting risks.

The Human Rights Watch explained that these weapons pose immediate threats to civilians and properties because of their wide area of effect. Furthermore, even after an armed conflict, these weapons pose threat, especially when submunitions fail to detonate.

Moreover, the International Committee of the Red Cross added that the high civilian casualties from cluster bombs come from the fact that submunitions can spread across a large area because they are either free-falling or can be carried by wind currents in inundated targets.

Submunitions that fail to detonate create post-combat risks to civilian lives. These explosives have the possibility to donate, thereby effectively making them inactive landmines while making reconstruction and redevelopment activities dangerous.


  • Human Rights Watch. 2022. “Cluster Munitions.” Human Rights Watch. Available online
  • International Committee of the Red Cross. 2011. “Cluster Munitions.” International Committee of the Red Cross. Available online
  • Winright, T. 2009. “The Morality of Cluster Bombing.” Studies in Christian Ethics. 22(3): 357-381. DOI: 1177/0953946809106237
  • United Nations Institute for Disarmament Research. 2008. The Humanitarian Impact of Cluster Munitions. United Nations Publications.