The US announced Friday it would provide Ukraine with cluster munitions, despite a Thursday plea from Human Rights Watch (HRW) for both Russia and Ukraine to cease their use of the deadly weapons. In a White House press briefing Friday, US National Security Advisor Jake Sullivan stressed that the US deferred the decision for as long as they could but ultimately found that the harm of a continued Russian offensive outweighed the risk of providing the munitions.

The US announced it would provide Ukraine with $800 million worth of weaponry to support its ongoing war effort against Russia. The package includes cluster munitions, which are large weapons—spanning rockets, bombs, missiles and artillery projectiles—that break apart and scatter smaller weapons over large areas. International human rights observers condemn the use of the munitions because, once fired, it is nearly impossible to control the scope of damage wrought by them. Russia and Ukraine have used cluster munitions since the start of the war in February 2022, which has drawn international criticism.

On Thursday, HRW doubled down on that criticism and pleaded with Russia and Ukraine to cease the use of cluster munitions in the war. Acting arms director at HRW Mary Wareham said, “Cluster munitions used by Russia and Ukraine are killing civilians now and will continue to do so for many years. Both sides should immediately stop using them and not try to get more of these indiscriminate weapons.”

But the US defended its decision to provide Ukraine with cluster munitions. On Friday, Sullivan said:

We recognize that cluster munitions create a risk of civilian harm from unexploded ordinance….But there is also a massive risk of civilian harm if Russian troops and tanks roll over Ukrainian positions and take more Ukrainian territory and subjugate more Ukrainian civilians because Ukraine does not have enough artillery. That is intolerable to us.

Sullivan further argued that there is a “big difference” between the cluster munitions provided by the US to Ukraine and the cluster munitions used by Russia. Sullivan claimed that the US-provided cluster munitions have a “dud rate”—meaning the cluster munition fails to explode upon impact—of only 2.5 percent. In comparison, Russian cluster munitions have a rate of between 30 and 40 percent.

However, HRW said, “The cluster munitions that the United States is considering sending to Ukraine are more than 20 years old, scatter over a wide area, and have a notoriously high failure rate, meaning they could remain deadly for years.”

The 2008 Convention on Cluster Munitions strictly prohibits the use, development, production, acquisition, stockpiling and transfer of cluster munitions. Notably, none of the three parties involved here—Ukraine, Russia or the US—are signatories to the convention. That said, the UN Office of the High Commissioner for Human Rights previously stated that the use of cluster munitions may still violate international humanitarian principles governing the conduct of hostilities. In other words, the use of cluster munitions may still amount to war crimes.

Regardless of the risk, Sullivan said President Joe Biden and his national security team unanimously decided to provide Ukraine with the requested cluster munitions. Sullivan claimed that US allies supported the move ahead of an upcoming NATO summit. However, Germany and France—members of NATO—indicated Friday that they will not follow suit in sending cluster munitions due to being signatories of the 2008 convention.