The principal weapon under consideration, an M864 artillery shell first produced in 1987, is fired from the 155mm howitzers the United States and other Western countries have provided Ukraine. In its last publicly available estimate, more than 20 years ago, the Pentagon assessed that artillery shell to have a “dud” rate of 6 percent, meaning that at least four of each of the 72 submunitions each shell carries would remain unexploded across an area of approximately 22,500 square meters — roughly the size of 4½ football fields.
“We are aware of reports from several decades ago that indicate certain 155mm DPICMs have higher dud rates,” said a defense official, one of seven Pentagon, White House and military officials who spoke on the condition of anonymity to discuss the sensitive pending decision. The defense official used the acronym for Dual Purpose Improved Conventional Munitions.
The Pentagon now says it has new assessments, based on testing as recent as 2020, with failure rates no higher than 2.35 percent. While that exceeds the limit of 1 percent mandated by Congress every year since 2017, officials are “carefully selecting” munitions with the 2.35 percent dud rate or below for transfer to Ukraine, should the president decide to do it, Pentagon spokesperson Brig. Gen. Patrick Ryder said Thursday.
A defense official who spoke on the condition of anonymity to discuss sensitive matters said details of the new assessments were “not releasable,” including how, when and where the tests were done, and whether they included actual firing exercises or virtual simulations. Military manuals say these weapons cannot be fired in training because they are part of war reserve stockpiles.
There is no waiver provision in the 1 percent limit Congress has placed on cluster munition dud rates, written into Defense Department appropriations since 2017. Biden would bypass it, according to a White House official, under the Foreign Assistance Act, which allows the president to furnish assistance, regardless of appropriations or arms export restrictions, as long as he notifies Congress that it is “vital to the security of the interests of the United States.”
Although the United States has used cluster munitions in every major war since Korea, no new ones are believed to have been produced for years. But as many as 4.7 million cluster shells, rockets, missiles and bombs, containing more than 500 million submunitions, or bomblets, remain in military inventories, according to estimates by Human Rights Watch drawn from Defense Department reports.
A 2022 Congressional Research Service report to lawmakers noted “significant discrepancies among failure rate estimates” of cluster weapons in the U.S. arsenal, with some manufacturers claiming 2 to 5 percent, while mine clearance specialists have reported rates of 10 to 30 percent.
Nonproliferation experts said that the Pentagon’s assessed 2.35 percent dud rate most likely refers to aging shells with updated fuses designed to improve their ability to self-destruct, but that it was impossible to know without access to the testing data.
Advocates who have warned against using cluster munitions say the claimed lower dud rates are the result of testing in idealized and unrealistic conditions that don’t account for real-world scenarios. The Army’s artillery manuals have said even the military’s own dud rates can increase depending on the angle of impact and type of terrain in which they fall.
Cluster weapons explode in the air over a target, releasing dozens to hundreds of smaller submunitions across a wide area.
More than 120 countries have joined a convention banning their use as inhumane and indiscriminate, in large part because of high failure rates that litter the landscape with unexploded submunitions that endanger both friendly troops and civilians, often for decades after the end of a conflict. The United States, Ukraine and Russia — which is alleged to have used them extensively in Ukraine — are not parties to the convention. Eight of NATO’s 31 members, including the United States, have not ratified the convention.
“It’s dismaying to see the long-established 1 percent unexploded ordnance standard for cluster munitions rolled back as this will result in more duds, which means an even greater threat to civilians, including de-miners,” said Mary Wareham, advocacy director of the arms division of Human Rights Watch.
“The lack of transparency on how this number was reached is disappointing and seems unprecedented,” Wareham said.
While Russia has used cluster munitions far more extensively, Ukraine has also allegedly deployed these weapons during the war, using its own Soviet-era stocks or shells obtained from other countries. A new HRW report released Thursday said Ukrainian use has “caused numerous deaths and serious injuries to civilians” in attacks in the city of Izyum and other locations in 2022. Ukraine has denied using cluster munitions.
The dud rate is both morally and legally key to supplying the weapons. In 2008, then-Defense Secretary Robert Gates issued a directive banning the production, use or transfer of cluster munitions with a failure rate of more than 1 percent and imposed a 10-year deadline for destroying existing weapons that exceeded that limit. Numerous nongovernmental and media reports have documented one subsequent use — against an al-Qaeda training camp in 2009 — although the United States has never confirmed nor denied the attack.
The Trump administration in 2017 reversed both the dud limit and the timeline for destroying any munitions that exceeded it, after which Congress adopted the legislative language banning any funding for the use, production or transfer of cluster munitions with a failure rate of more than 1 percent, even as major defense manufacturers canceled production contracts under pressure from shareholders and public opinion.
In an interview Wednesday, Ukrainian Defense Minister Oleksii Reznikov said obtaining a significant supply of the weapons has become crucial to Kyiv’s ongoing counteroffensive.
The United States and other Western donors have sent millions of non-cluster howitzer shells to Ukraine, but stockpiles are running low and manufacturing cannot keep up with demand. It “is not enough,” Reznikov said. “The Russians use three or four times more artillery shells of different calibers than we do. And we must conserve because we can’t shell as intensively,” he added.
“Since these projectiles are effective,” Reznikov said of cluster munitions, “they will allow us to make up this difference.” The Russians “are using them against us, so for our self-defense we have full right to use the same munition.”
“This is just for where there are fields, because it’s very important not to bring harm to the civilian population,” Reznikov said. “We won’t use them before the de-occupation of a city.”
As Ukraine’s pleas for the weapons have increased in recent months, they have been met with both agreement and disapproval by U.S. lawmakers. In late March, a group of senior Republicans, including the chairmen of the House Armed Services and Foreign Affairs committees, and the ranking members of the counterpart Senate committees, said they were “deeply disappointed” in the administration’s “reluctance” to provide the weapons.
“Providing DPCIM,” they wrote in a letter to Biden, “will allow Ukraine to compensate for Russia’s quantitative advantage in both personnel and artillery rounds, and will allow the Ukrainian armed forces to concentrate their use of unitary warheads against higher-value Russian target.”
Others, including many Democrats, are less enthusiastic. Rep. Adam Smith (D-Wash.), the ranking member of the House Armed Services Committee, said that he was open to supplying the munitions to Ukraine but that he still had not been provided additional information about what is being sent and how it will be used.
The administration is “trying to send the ones with the lowest possible dud rate, which makes sense,” Smith said in an interview Monday. “The question is: Are there munitions that have that low dud rate? I’ve been told repeatedly that … yes, there are.”
“The Russians have been dropping these things with dud rates that are a hell of a lot higher than 8 percent all across Ukraine for a year and a half now,” he said.
Daryl Kimball, executive director of the Arms Control Association, which, along with Human Rights Watch, compiles information for the Landmine and Cluster Munition Monitor, a Swiss-based international organization, noted the Pentagon’s failure to release any information on its new assessments and transfer plans. “We requested consultations about this months ago in a formal letter,” he said, but had received no reply.
Provision of the weapons has also been controversial within the administration. In remarks to the U.N. Security Council a week after Russia’s February 2022 invasion, Linda Thomas-Greenfield, U.S. ambassador to the United Nations, accused Moscow of using “exceptionally lethal weaponry,” including cluster munitions, that “has no place on the battlefield” and is “banned under the Geneva Convention.” Her “no place” reference was later excised from the State Department’s official transcript of the speech, which was also amended to note that the Geneva Conventions ban cluster use “directed against civilians.”
The administration began to soften its position on providing cluster munitions this past spring as the shortage of standard artillery munitions became more acute. Biden said in May that cluster weapons “may” be considered, and Secretary of State Antony Blinken is said to have recently dropped his opposition.
NATO Secretary General Jens Stoltenberg denounced Russia’s reported use of cluster weapons early in the war, saying, “This is brutality, this is inhumane, and this is violating international law.”
The administration has worked in recent weeks to allay allied concern over the transfer of the weapons to Kyiv, according to a second White House official. “The president’s top priority is maintaining unity among our allies and partners in support of Ukraine, and we would not take any actions that would undermine that priority,” the official said. As a result of allied consultations, “if we were to move forward” with cluster munitions, “we are confident that would not be an issue.”
The U.S. military has long considered cluster munitions a useful battlefield weapon. That position was reaffirmed in March testimony before the House Armed Services Committee by Army Gen. Christopher Cavoli, head of the U.S. European Command and supreme allied commander of NATO. “We call it dual-purpose, because it releases bomblets, some of which are anti-personnel fragmentation grenades and some of which are shaped charges that attack vehicles from above,” Cavoli said. “It’s a very effective weapon.”
The munitions can be an attractive option for commanders to destroy troops or equipment in big groups, or when a target can’t be pinpointed by precision artillery. But they also come with drawbacks for the forces using them.
Army artillery doctrine warns that DPICM submunition duds “can pose significant risks to friendly personnel and equipment.” A 2017 manual puts the overall dud rate for cluster rounds at 2 to 3 percent, while warning the rate could increase if procedures aren’t followed or if uneven terrain disturbs the angle required for detonation.
In addition to the risk of civilians picking up unexploded duds long after a battle, they can also pose more immediate danger to the forces deploying them. “There’s definitely a lot of tactical risks in employing these types of munitions. It limits your ability to maneuver, and limits your ability to maneuver quickly, because you have to be clearing a bunch of UXO,” or unexploded ordnance, said a former U.S. Army artillery officer, who spoke on the condition of anonymity to avoid conflicts with his current employer. “It’s gonna slow you down, it’s gonna limit the ways in which you can exploit success.”
The U.S. history of what are considered “friendly fire” incidents is a concern: Several U.S. service members were killed during and after the Gulf War by unexploded munitions, according to a 1993 Government Accountability Office report, which said the Army did not hold force-wide training to recognize submunitions on the ground before the invasion.
“Someone within DOD knows the actual dud rate,” the former officer said, “and I hope that would be communicated honestly and accurately to any Ukrainian unit receiving these types of munitions.”
Isabelle Khurshudyan in Kyiv and Abigail Hauslohner contributed to this report.