Too little but not too late. Cluster munitions can help Ukraine turn the tide if the United States ramps up supplies

Cluster munitions come in different varieties, but to observers of the war in the Ukraine, the most familiar will be those fired by artillery. During the Cold War the United States procured huge quantities of both ICM (Improved Conventional Munition) & DPICM (Dual Purpose Improved Conventional Munition) artillery rounds. The dual purpose in the latter refers to it’s anti-personnel and anti-armor effects. These rounds are filled with dozens of small “grenades” or submunitions, instead of a unitary mass of high explosive (HE). They were fired in large numbers in the Vietnam War and later during the 1st Gulf War in 1991, to good effect in both.

According to US Army analysis of combat in Vietnam, for every 13.6 155mm unitary high explosive shells fired, 1 enemy would be killed, compared to just 1.7 for a 155m ICM shell. For an 8-inch (203mm) ICM the ratio was even more favorable, with just 0.8 rounds being required per kill. US Army Captain David Brown, who commanded a M109 155mm self propelled howitzer battery in the 1st Gulf War described DPICM’s effects as follows: “The … destruction of [DPICM] is almost beyond belief without actually experiencing it falling on you.”

By 1994 the US Army & US Marine Corps together still had over 6.3 million ICM & DPICM rounds in good condition. However, following the 2003 Invasion of Iraq, concerns about unexploded ordnance left by undetonated submunitions created pressure on the US Government to address that problem. In June 2008, then Secretary of Defense Robert Gates implemented a requirement for the US military to, within 10 years, demilitarize its stockpile of cluster munitions with a failure, or “dud” rate exceeding 1%. DPICMs fired during the 1st Gulf War were found to have around a 5% dud rate, so much of the United States’ stockpile was not compliant with the policy.

Thankfully on November 30th, 2017, then US Deputy Secretary of Defense Patrick Shanahan issued a memorandum which eliminated the requirement to demilitarize the noncompliant cluster munitions. The requirement was also nowhere close to being met when it was eliminated, so the US still maintains a considerable inventory of cluster munitions. While the precise number is unknown, a March 2023 Congressional letter to President Biden stated that the inventory of DPICMs is nearly 3 million rounds.

That letter was an appeal from Congressional Republican leaders to President Biden to provide DPICMs to Ukraine. Advocates, myself included, had been making that argument since the summer of 2022. Senior Ukrainian military officers were publicly asking for them as early as December 2022; though we would learn in January 2023 that Turkey had begun supplying Ukraine with M483A1 155mm DPICMs in November 2022. Ukraine of course had its own existing stockpile of cluster munitions as well, but none of these arguments swayed President Biden. It wasn't until the summer of 2023 that the Pentagon finally acknowledged the utility of DPICMs for Ukraine.

Ultimately, it was concerns about the US’ shrinking stockpile of unitary HE 155mm shells that tipped the balance. On July 7th, then Under Secretary of Defense for Policy Colin Kahl announced the decision to provide Ukraine with DPICM, describing them as a way to “bridge the gap” between the US’ insufficient production of 155mm ammunition, to a future date when it would be sufficient to meet Ukrainian ammo requirements. In an attempt to placate some concerns about unexploded ordnance, he also announced that only munitions with a dud rate below 2.35% would be provided, and that they had “hundreds of thousands” of shells available that met this standard.

Not two weeks after the decision, videos of them being used in the field began to emerge, followed by testimony of their impact. “They are super efficient,” one Ukrainian marine told the New York Times. “When our guys see how we use them against the enemy, their spirits soar.”

White House National Security Council Spokesman John Kirby described Ukrainian employment of them as “quite effective”, adding “They are actually having an impact on Russia's defensive formations and Russia's defensive maneuvering.”

On October 20th, video posted on X that was recorded by a Ukrainian reconnaissance drone captured DPICMs scoring a direct hit on a column of Russian infantry advancing through an open field. American artillery officer “CJ” captioned it: “There’s too many videos like this to count. US cluster munitions in the hands of skilled Ukrainian artillerymen are shredding the Russians attacking Avdiivka to pieces.”

These are the situations where the advantage of DPICM over unitary HE ammunition is extremely clear. If there was still any doubt though, just read what the Russians have to say. “It is cluster shells that are now knocking out a huge mass of our infantry,” a Russian instructor for a penal unit explained. “cluster shells have a very favorable ratio of the quantity used to the quantity of the fire damage inflicted on infantry.”

This corroborates both the US Army’s own conclusions from Vietnam, and the videos from the front. Small numbers of DPICMs can achieve the same or better effects than a much larger number of unitary shells would be able to.

The availability of DPICMs allows Ukraine to conserve their limited supply of artillery ammunition, and reduces wear on their gun barrels, which keeps them operational for longer. These benefits are being needlessly limited though, by the relatively small number of DPICMs that have been made available to Ukraine by the United States. Indeed, the US stockpile is nearly 3 million shells. “Hundreds of thousands” of shells with a dud rate of less than 2.35% could be as low as 200,000 or as high as 900,000, but in either case that still means that a super majority of the US’ inventory is off the table for Ukraine. Nor should Ukraine expect to receive all of the “hundreds of thousands” of shells that have been set aside for them. Since the first drawdown package when they were first provided on July 7th, additional DPICMs have only been provided once, on September 21st. The Pentagon has been asked about this on several occasions and continues to respond that DPICMs are not being provided unannounced.

This slow drip of ammunition is sadly a familiar story. The story of DPICMs is the same as that of the 155mm howitzers that fire them, the High Mobility Artillery Rocket System, the M1 Abrams main battle tank, the M2 Bradley infantry fighting vehicle, and the Army Tactical Missile Systems, which is the other cluster munition that the United States has provided to Ukraine. All only arrived in Ukrainian hands in very limited quantity, after months or over a year of internal debate within the Biden Administration. This indecision has significantly reduced the effect that these weapons have had on the war. While still effective, they fail to deliver any significant defeats to Russian forces, who have made good use of the breathing room afforded to them to adapt and react to Ukraine’s new weapons.

Russia’s latest response is their own cluster munitions. They of course have always had them, but in the earlier stages of the war they were often being utilized to strike civilian targets, rather than military. One of the more famous pictures from the war shows a mountain of debris from rockets fired at Kharkiv, many of them cluster munition dispensers. The Russian penal unit instructor had this to say about their BM-30 Smerch multiple rocket launchers: “we have a wonderful ‘Smerch’ system, which in fact does not affect the general state of affairs at the front.”

Whatever the shortcomings Smerch has though, the Russians have developed an effective new method of deploying cluster munitions on the frontline. Last month, the Russians began equipping their RBK-500 bombs with UMPK standoff guidance kits to increase the precision of their airstrikes and the distance at which they can be launched from. This allows the Russians to deliver the destructive power of cluster munitions anywhere in the theatre of operations, at short notice and with both speed & precision. Whereas Ukrainian artillerymen can only fire their DPICM rounds at targets within the immediate range of their guns, Russian fighter jets can be dispatched to strike anywhere on the battlefield.

The benefit accrued from the standoff glide kits must be further emphasized as well. Whereas dropping unmodified “dumb bombs” would require the aircraft to fly over target, potentially exposing itself to anti aircraft fire, with the glide kits, they can deploy their payloads at a safe distance away from the frontline. This potentially allows the Russian Air Force to fly more missions each day.

The RBK-500 can carry different submunitions, but the primary choice has been the ShOAB-0.5M, which is very similar both in appearance and function to the American M74 Anti‐Personnel Anti‐Materiel submunition carried by M39 & M39A1 ATACMS. The RBK-500 can carry up to 565 ShOAB submunitions, which disperse in the air in a circular pattern like 155mm DPICMs or ATACMS do. Upon detonation, each ShOAB sends approximately 300 tiny steel balls flying. According to Fighterbomber, a well sourced Russian military blogging channel, Russian aircraft usually just carry 2 RBK-500s on a combat mission, which in their estimation is inadequate. They suggested increasing it to 4, to improve the effectiveness of their airstrikes. This seems to have been acted on, as video of just that has emerged.

To make matters worse, Ukrainian officials have said that these Russian precision guided glide bombs are “almost impossible to shoot down”. This may be an overstatement of the problem, at least from a technical perspective. Ukraine’s air defense dilemma is not that their available systems are not capable, but rather, unsurprisingly, that they are not numerous enough. Ukraine has concentrated their air defenses on protecting its cities and other critical infrastructure, leaving insufficient resources to protect frontline units. British Military intelligence has noted increased Russian deployment of these cluster bombs, particularly in the Vulhedar and Avdiivka areas, where some of the most intense fighting is taking place.

Russia’s guided RBK-500s are far from a war winning weapon either, but they demonstrate that the Russian military continues to learn and improve their combat effectiveness. If Ukraine is to be victorious, it’s essential that they be provided with every qualitative and quantitative advantage within the capabilities of the supporting coalition. Delivering at least 1 million DPICMs and the 1200 “expired” ATACMS in US inventory would ensure that Ukraine has sufficient artillery and precision strike ammunition for their next offensive. The alternative is that Russia will continue to have an advantage in the amount of ordnance they can deliver onto Ukrainian positions.

This problem is within the capacity of the Ukraine supporting coalition to fix. How much military aid we provide them is the only thing that is completely within our control. Both sides have demonstrated the effectiveness of cluster munitions. The Ukrainians have made extremely good use of the limited supply provided to them, but if they do not receive substantially more of them, then Russia will certainly be able to achieve greater impacts on the battlefield with their own cluster munitions. Now is not the time to fold, it’s time to go all in.