Washington will supply Ukraine with cluster munitions as part of a military aid package worth $800 million to help fight off the Russian invasion.

In a statement sent out to reporters on Friday, US Secretary of State Antony Blinken said that the weapons and equipment in this new aid package were "essential to strengthening Ukraine's brave forces on the battlefield and helping them retake Ukraine's sovereign territory and defend their fellow citizens."

German Foreign Minister Annalena Baerbock rejected supplying such weapons to Ukraine on Friday. Speaking in Vienna, Baerbock said the government stood by the Oslo Convention, which is considered a milestone in the fight against the controversial explosives. An international ban on them came into force in 2010.

To date, 110 countries have joined the Convention on Cluster Munitions, and a further 13 nations have signed but not ratified the Convention — so they are not yet obliged to implement it. Signatories commit to neither produce, stockpile nor use the weapons.

Who prohibits cluster munitions and who doesn’t?

However, the world's largest countries ―including Russia, the US, China, India and Pakistan ― and also Ukraine have not signed. Asia, the Middle East, North Africa and eastern Europe all have a low percentage of members.

Despite the Convention's adoption, the proportion of cluster munitions victims has increased significantly, especially in recent years, due to escalated use of the bombs but also better documentation thereof. In 2020, for instance, half of all cluster munitions casualties were recorded in Syria — where the bombs have been used since 2012 — both from direct attacks and through previously unexploded residual components.

According to Human Rights Watch, Russian troops have “extensively used cluster munitions in Ukraine, killing many civilians and causing other serious civilian harm." Ukrainian forces had also used them, causing “numerous deaths and serious injuries to civilians,” the international non-governmental organization said.

Handing such munitions over to Kyiv would "inevitably cause long-term suffering for civilians and undermine the international opprobrium of their use,” the group continued.

Some military experts believe cluster munitions could help Ukraine in its counter-offensive against Russian troops holed up in trenches.

What are cluster munitions?

Cluster munitions are dropped as bombs from airplanes or fired as rockets from howitzers, artillery guns and rocket launchers. They contain hundreds of smaller submunitions, known as “bomblets”, that then fall indiscriminately over wide areas that range in size from a few soccer fields to several hectares of land. Cluster bombs not only kill soldiers, but civilians, including many children.

Such munitions have been in use since World War Two and were deployed extensively in the Vietnam War, for example. During that conflict, the US dropped some 260 million of them on neighboring Laos, making it the country with the world's highest level of cluster munition contamination.

According to Humanity & Inclusion, a France-based charity organization also known as Handicap International, only about 40% of the smaller bomblets contained in a cluster bomb detonate upon impact. The undetonated ones can still pose a deadly threat decades after they are deployed: The munitions remain ready to explode and can maim or kill a person at any time. They work in a similarly disastrous way to landmines, sometimes rendering affected areas uninhabitable. Some areas of Laos, for example, remain completely contaminated decades after the end of the war.

Civilian populations are especially affected by the use of cluster munitions. The 2022 monitoring report compiled by the Cluster Munition Coalition found that 97% of victims were civilians and 66% of those injured or killed were children. As of August 2022, Ukraine was the only country where cluster munitions were being deployed, according to the report.

Who produces cluster munitions?

Sixteen countries currently produce cluster munitions and have yet to commit to stopping, according to the Cluster Munition Coalition report. They are Brazil, China, Egypt, Greece, India, Iran, Israel, North Korea, Pakistan, Poland, Romania, Russia, Singapore, South Korea, Turkey and the United States. Russian forces deployed at least two types of newly developed cluster munitions in Ukraine last year, the report continued.

Ahead of the announcement on the US aid package, the executive director of the US Arms Control Association spoke out against the transfer of such weapons. Sending them “would be escalatory, counterproductive, and only further increase the dangers to civilians caught in combat zones and those who will, someday, return to their cities, towns, and farms," Daryl Kimball said.

This article was originally written in German. The English version was published on June 15, 2022, and updated with developments in the Ukraine war on July 7, 2023.