Hundreds of cluster munitions have been used on Ukrainian territory since the full-scale war began in February 2022 as countries across the world have continuously condemned their deployment. Now it appears that the munitions the United States is sending to Ukraine since July to slow Russian military advances on Ukrainian territory is raising more than the usual concern expressed by the United Nations about the weapons’ use and their possible escalation of the war.

“I would like to emphasize here that reports related to the transfer and use of cluster munitions are very concerning,” said Izumi Nakamitsu, the UN high representative for disarmament affairs, at a Security Council meeting on Aug. 17. “The Spokesperson of the Secretary-General has called for these types of munitions to be consigned to history and not to be used.”

The meeting was requested by Russia to discuss weapons flows from the West into Ukraine; it is not the first time that Russia has asked for such a session since its invasion 18 months ago, as it tries to deflect that it instigated the war — a narrative that the US envoy to the UN called “hypocritical and preposterous.” In Russia’s speech to the Council, it didn’t mention its own use of artillery against its neighbor.

The cluster munitions that President Joe Biden agreed to send — amid continuing controversy — from the United States to Ukraine are reportedly hindering Russian troops’ progress on the frontline, according to The Washington Post and other media. Biden justified the supply of the weapons based on reports that Ukrainian troops are short on artillery. Russia has been using the weapons in Ukraine in its invasion and President Vladimir Putin has pledged to keep doing so if Ukraine uses its new American stockpile. Ukraine used the weapons early in the war but reportedly on a lesser scale.

In 2008, the Convention on Cluster Munitions was ratified to prohibit all use, transfer, production and stockpiling of the weapons. The treaty has been signed by 108 nations, including such key European countries as France and Germany, but Russia, Ukraine and the US have refused to join, along with India, Iran, Saudi Arabia, United Arab Emirates, Brazil, China, Israel and Pakistan, among others. The Ottawa Treaty of 1997, also known as the Mine Ban Treaty, bans antipersonnel mines, but Russia and the US aren’t party to that agreement either, while Ukraine is. Cluster weapons have been used in such recent wars as Syria and the Saudis in Yemen.

In 2018, Nakamitsu said that the cluster ban treaty was an example of “disarmament that saves lives.”

Cluster munitions are considered notorious for their ability to inflict indiscriminate harm not only during a conflict but also afterward as they can lay hidden in the ground undetonated until innocent people — including children — happen to stumble on them and lose their limbs or lives.

The weapons are usually deployed as bombs which, when opened, eject submunitions that later detonate and scatter bomblets over a large area. Each submunition can damage equipment, structures and vehicles and severely maim or kill military personnel and civilians. They appear to be working against Russian troops now. As John Kirby, the Pentagon spokesperson, said in late July of their deployment, “We have gotten some initial feedback from the Ukrainians, and they’re using them quite effectively.”

Kirby added that the weapons were having an “impact on Russia’s defensive formations and Russia’s defensive maneuvering.” Although US weapons makers stopped producing the munitions in 2016, the US supply to Ukraine is drawing from a stockpile that also contains older, more dangerous versions of the weapon, according to media reports and human rights organizations.

Yet the UN remains steadfast in its criticism of the use of cluster munitions anywhere, including Russia’s war in Ukraine. It has assertively spoken against reliance of the explosive weapons for years, and in his message on the International Day for Mine Awareness and Assistance in Mine Action, on April 4, Secretary-General António Guterres said:

“Even after the fighting stops, conflicts often leave behind a terrifying legacy: landmines and explosive ordnance that litter communities. Peace brings no assurance of safety when roads and fields are mined, when unexploded ordnance threatens the return of displaced populations, and when children find and play with shiny objects that explode.”

Nakamitsu reminded the Security Council on Aug. 17 of the need for “supply chain transparency” to avoid the risk of all weapons being diverted or resold to unauthorized end-users. She also stressed the major danger that cluster munitions pose to civilians, reminding Ukraine — whose UN delegation participated in the meeting — and Russia that under international humanitarian law, states are prohibited from targeting civilians or civilian infrastructure and are obliged to take all precautions to minimize such risks “to avoid, or at least minimize” civilian injuries, deaths and “damage to civilian objects.”

In the meeting, Russia said that “Western suppliers . . . ignore all their obligations to trace the end user of the supplied systems.”

Dmitry Polyanskiy, the country’s deputy permanent representative, devoted a portion of his remarks in the Council on Ukraine’s use of cluster munitions, indirectly acknowledging their effectiveness, saying they were being deployed in areas with “no military targets” and that they offered “no special advantages on the battlefield,” such as contested parts of the Donetsk region. Instead, they were used to “terrorize the civilian population.” Although he gave no specifics, media reported early this month that cluster munitions fired by Ukraine hit a university in the area, although Reuters said the information could not be verified.

Polyanskiy noted: “Unlike that of the United States, Russia’s position on the use of cluster munitions is consistent and prescribes full compliance with IHL norms and requirements.” He provided no proof of Russia’s compliance with international humanitarian law, as the country faces nearly daily accusations of war crimes committed in Ukraine.

“Assurances of the United States authorities that the cluster weapons they supply to Ukraine will allegedly not be used in violation of the IHL are a blatant lie,” Polyanskiy added.

Serhii Dvornyk, a top diplomat for Ukraine’s mission to the UN, did not address the issue of cluster munitions directly but said that his country was engaged in “an existential battle for survival.”

US Ambassador Linda Thomas-Greenfield didn’t mention cluster bombs directly, either, but she said: “Western weapons provided to Ukraine to prevent Russia’s brutalization of Ukraine’s people are not the cause of this war nor are they prolonging this war: that responsibility is the Kremlin’s alone. Russia remains the sole obstacle to peace in Ukraine.”

Although a US Defense Department official said the US had received “assurances in writing” that Kyiv would avoid urban areas when firing US-supplied cluster munitions, Human Rights Watch says both Russia and Ukraine have caused civilian deaths from use of cluster munitions in the war, long before the American munitions arrived.

A UN report released last spring found that Ukrainian armed forces used the weapons in attacks on Izium between March and September 2022, while a Russian cluster munition targeting the train station in Kramatorsk killed 50 civilians and injured 100 more, including children. According to Nakamitsu, the war in Ukraine has claimed approximately 26,384 civilian casualties, mostly from “the use of explosive weapons with wide area effects” such as cluster bomblets.

Biden recently committed $91.5 million to demining aid to Ukraine. But Nakamitsu urged the warring parties to avoid “indiscriminate harm” from unexploded ammunition to prevent “further instability and insecurity in Ukraine, the region and beyond.”

On July 5, Guterres said at a fund-raising appeal for the postwar reconstruction of Ukraine, “We are also working with the Government of Ukraine to tackle the insidious threat of unexploded ordnance, landmines, and cluster munitions.”

Just a few days later, the US announced it would send cluster weapons to Ukraine.

This article was updated to be more precise about how cluster munitions work and that the Ottawa Treaty bans anti-personnel mines and not cluster munitions per se. 

Arthur Bassas

Arthur Bassas is a researcher and writer who graduated from St. Andrews in Scotland, majoring in international relations and terrorism. He lives in Brooklyn, N.Y., and speaks English and French.