Explainer: why cluster bombs used in Ukraine have been banned by 120 countries

Cluster bombs have a high deactivation rate, meaning they have a failure rate of up to 40%.

White House spokesman John Kirby has said that the controversial cluster weapons supplied by the United States are being used by Ukraine in its retaliatory strike against Russia. “We’ve had some preliminary feedback from the Ukrainians, and they’re using them quite effectively,” a White House national security spokesman said. John Kirby told reporters on Thursday.

Although Moscow, which previously said it would use “similar” weapons if the United States supplied Ukraine with cluster bombs, has yet to react to the announcement, the White House official’s claim has drawn some allies and has caused outrage among humanitarian groups.

What are cluster bombs?

A cluster bomb opens in the air and releases smaller “bombs” over a wide area. The bombs are designed to take out tanks and equipment as well as troops while attacking multiple targets at the same time.

But what makes their use a concern is that they have a high dust rate, meaning they have a failure rate of up to 40%, leaving the ground littered with unexploded bombs. Washington says the cluster munitions it is sending to Ukraine have a failure rate of less than 2.35%.

Is the use of cluster bombs a war crime?

The use of cluster bombs by itself does not violate international law, but using them against civilians may be a violation. As with any military conflict, determining a war crime requires looking at whether the target was lawful and whether precautions were taken to avoid civilian casualties.

More than 120 countries have joined the Convention on Cluster Munitions, and have agreed not to use, produce, transfer or store the weapons. However, the US, Russia and Ukraine have not signed the agreement.

Where have they been used?

Cluster bombs have been deployed in several recent conflicts in which US forces were involved.

According to Human Rights Watch, both Moscow and Kiev have used cluster munitions during what Russia calls “special military operations” during the nearly 17-month conflict in Ukraine.

Cluster bombs were also used by Syrian government troops against opposition strongholds during the country’s civil war, often targeting civilian targets and infrastructure.

Israel has also been criticized for its use in civilian areas in South Lebanon, including during the 1982 invasion. According to HRW, Israel fired nearly four million cluster munitions into Lebanon during its months-long war with Hezbollah in 2006.

The Saudi-led coalition in Yemen reportedly also used cluster bombs in the war with Iran-backed Houthi rebels who have devastated the southern Arab country.

America has also used weapons during the attack on Afghanistan. During the first three years of the conflict, the US-led coalition is estimated to have dropped more than 1,500 cluster bombs in Afghanistan.