The Economist explains

Why are cluster munitions so dangerous?

Despite efforts to ban them, the weapons are being used in Ukraine

SLOVIANSK, UKRAINE - JULY 03: Fire burns at a shopping mall after it was struck by a missile on July 03, 2022 in Sloviansk, Ukraine. The attack was one of many in the city early Sunday afternoon, which targeted residential neighborhoods, destroyed homes and left at least 6 people dead and 15 injured. (Photo by Scott Olson/Getty Images)

ON JUNE 30TH the mayor of Slovyansk, a city in Ukraine’s eastern Donetsk province, said that four people in a residential area had been killed by Russian cluster munitions. Both sides in the war have reportedly used the weapons, though Russia has been accused more often. Despite efforts to ban the bombs, other armies also employ them. What are cluster munitions, and why are they so dangerous?

A single warhead is lethal close to the point of detonation, but less effective further away. This is ideal for destroying a point target such as a bunker, vehicle or building, but is less use against a column of vehicles or spread-out infantry. Cluster munitions, on the other hand, scatter grenade-sized “bomblets” over a large area, cancelling out aiming errors. That makes them more likely to hit civilians. Human-rights organisations say that the use of cluster munitions in populated areas is a violation of international humanitarian law because they cause indiscriminate destruction.

The weapons were first used in the second world war, becoming commonplace in the years after. “Steel rain” was highly regarded by Allied forces in the Gulf War of 1991 and the invasion of Iraq in 2003. A single M26 rocket could scatter 644 grenades over an area roughly twice the size of a football pitch, and the Multiple Launch Rocket System can fire volleys of 12. Each was capable of destroying a light-armoured vehicle and spraying shrapnel. But they also left a deadly trail. The bomblets had a reported failure rate of between 5% and 23%; one volley could leave hundreds of unexploded bombs. In Ukraine, Russia’s artillery and short-range BM-21 Grad launchers typically fire rockets with cheaper unitary warheads, but longer-range Smerch rockets, as well as Tochka and Iskander ballistic missiles, sometimes have cluster warheads. Ukraine’s armed forces also inherited a stock of cluster munitions after the fall of the Soviet Union, including the same Smerch rockets and Tochka missiles.

The Convention on Cluster Munitions, an international treaty signed in 2008, bans them, but neither Russia nor Ukraine is among the 110 countries party to it. Nor is America (although it hasn’t used them since the invasion of Iraq) and in 2017 Donald Trump’s administration got rid of restrictions on the use of the weapons. Despite this, the Pentagon has developed alternative warheads for its rocket-launch systems. These GPS-guided munitions are being supplied to Ukraine for use instead of older cluster warheads. They are based on a technology known as “lethality-enhanced ordnance”, and use computer modelling to tailor the warhead’s effects. The munition detonates at a set height and the tungsten casing, scored in a computer-generated pattern, disintegrates into 182,000 diamond-shaped fragments. (These work in a similar way to flechettes, a brutal weapon being used by Russia.) One version also contains tungsten penetrators, small metal fragments arranged to destroy vehicles.

America claims these new munitions are as effective as cluster warheads, without leaving behind dangerous unexploded bomblets. This may reduce the temptation for Ukrainian forces to use stockpiled cluster weapons, especially on Ukrainian soil. But Russia is likely to continue, possibly seeing their indiscriminate effects as psychological warfare. Ukraine’s emergency service said it had destroyed 98,864 items of unexploded ordnance by May 9th. According to the Washington Post, 29 workers died in the process during the first seven weeks of the war. Cluster weapons will leave large parts of the country contaminated. Long after the war is over, civilians and demining workers in Ukraine will be killed and injured by munitions now being used.

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This article appeared in the The Economist explains section of the print edition under the headline "Why are cluster munitions so dangerous?"

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