Giving Ukraine Cluster Munitions is Necessary, Legal and Morally Justified

Guns blazing: Ukrainian troops fire heavy artillery at Russian positions along the frontlines of the war in Bakhmut. Image: Zuma Press / Alamy

Cluster munitions would be valuable in breaking through Russian trenches, while the threat to civilians is negligible amid Russia’s mass emplacement of unmarked minefields.

The news that the US will provide Ukraine with cluster munitions has sparked a flurry of objections from campaign groups. Many of the objections demonstrate a lack of understanding as to the context of how these weapons will be employed if provided to the Armed Forces of Ukraine (AFU). The military utility of these munitions to Ukraine is clear, while their use renders the foremost objections irrelevant. Given that the US military has consistently advised the Biden administration to send these weapons – and that there has been no significant change to the circumstances on the ground – the real question is why dual-purpose improved conventional munition (DPICM) rounds were not provided to Ukraine in time to make a difference to the current offensive.

The Military Context

Ukraine is currently undertaking a major offensive, seeking to break through three successive lines of Russian defences to liberate occupied Ukrainian territory. To do this, the AFU must fight their way through over 30 kilometres of complex, unmarked minefields, across tank obstacles, and into extensive trench lines, covered by Russian UAVs, artillery and helicopters. Progress is critical to preventing Russia from indefinitely protracting the conflict. Therefore, there is a direct correlation between enabling Ukraine to succeed on the battlefield now, and creating the necessary preconditions for a viable peace.

To break the defence line, Ukrainian artillery is critical for suppressing Russian indirect and direct fire, thereby enabling Ukrainian troops to assault Russian trenches. Not only does Ukraine field fewer artillery pieces than the Russian military, but finite stocks of ammunition and replacement howitzer barrels among Ukraine’s international partners are a major constraint on how long Ukraine can maintain a high tempo of operations. Maximising the efficiency of Ukrainian artillery fire is, therefore, a critical factor in determining the outcome of the conflict.

DPICMs for 155mm howitzers and multiple launch rocket systems greatly multiply the efficiency of artillery fire against entrenched troops. As an example, according to US Army data on engagements during the Vietnam War, the number of conventional high-explosive (HE) 155mm rounds fired for each enemy soldier killed in combat was 13.6, compared to only 1.7 for DPICM shells. When fired against Russian defensive fortifications in Ukraine, a conventional artillery shell has a very low probability of killing Russian troops unless it lands directly in a trench. Even if an HE round does land in a trench, it will only spread shrapnel in the trench sector within line of sight of the point of detonation. A DPICM round, by contrast, spreads 72 submunitions over a significant area. This greatly increases the chances of multiple submunition blasts directly impacting troops in trenches, providing much greater lethal and suppression effects.

With each barrel having a life of around 1,800 rounds, giving Ukraine DPICMs will mean it has to fire fewer total rounds for a given battlefield effect, allowing it to sustain the fight for significantly longer

The increased effectiveness of each artillery shot, however, is not even the most significant logical driver for providing Ukrainian forces with DPICMs from a military point of view. Rather, the most significant driver is the operational impact on Ukrainian artillery ammunition stockpiles and barrel life. With each barrel having a life of around 1,800 rounds, giving Ukraine DPICMs will mean it has to fire fewer total rounds for a given battlefield effect, allowing it to sustain the fight for significantly longer. It also makes a large amount of currently unused munitions in the stockpiles of Ukraine’s international partners available, and would reduce the consumption rate of increasingly stretched conventional HE 155mm stocks – buying crucial time as NATO countries struggle to expand munitions production. This is vital given Russia’s current strategy of attempting to dig in and prolong the conflict – a strategy specifically designed to exhaust Western capacity to supply the AFU with sufficient munitions and equipment to keep fighting. Russia, by contrast, is already mobilising its defence industry and has an existing capacity for large-scale munitions manufacture.

Legal and Ethical Considerations

There are two objections advanced by activist groups like Human Rights Watch (HRW) to providing Ukraine with DPICMs. Firstly, there is the allegation that DPICMs are prohibited and their use may amount to a war crime. Secondly, there is the claim that their use will kill Ukrainian civilians. Both arguments are tenuous.

The US, Ukraine and Russia have never signed the Convention on Cluster Munitions, in which 111 states agreed not to use cluster munitions. Furthermore, Poland and Romania – two NATO members through which munitions would likely have to flow in order to reach Ukraine – also never signed the treaty. Therefore, no one likely to be involved in the supply, transit or future use of these weapons is bound by any specific legal prohibition against their use.

HRW argues that because some DPICM submunitions will fail to explode, they are inherently indiscriminate. The problem with this argument is that a significant proportion of other munitions also fail to explode. In fact, up to one in five of Russia’s munitions stocks are assessed by the Russian military to be unsafe due to their age and poor condition, and yet these are routinely fired at Ukraine. HRW’s unexploded ordnance argument is one that would apply equally to a wide range of explosive weapons already in use in the conflict, and it is therefore illogical as a reason to specifically reject the provision of DPICMs.

DPICM provision will not only increase Ukrainian military effectiveness against dug-in Russian forces, but will also help alleviate Ukrainian and wider NATO ammunition shortfalls and barrel constraints

HRW is also wrong that it is not possible to discriminate between civilian and military targets when using DPICM rounds. In the first weeks of the war, for example, Russia fired thousands of BM-30 rockets and other cluster munition rounds directly onto Ukrainian civilian population centres, especially Kharkiv. This would have been a war crime even if it were done with unitary munitions, but unexploded submunitions have undoubtedly posed a sustained risk to civilians in these areas. Ukraine, by contrast, is looking to employ these weapons against Russian field fortifications in open countryside that are already surrounded by unmarked minefields and unexploded Russian ordinance.

The point is that these areas will be marked as dangerous for civilians whether there are unexploded DPICM submunitions present or not, and Ukraine will have to conduct a deliberate clearance operation after the war irrespective of whether DPICMs are used. It is, of course, important that Ukraine marks any areas where DPICMs are used. However, given how the Ukrainian state has managed a large number of mines emplaced across other liberated territories, there is no evidence to suggest that the Ukrainian state is complacent about its responsibility to protect its own civilian population, or that it is likely to be negligent in its future duties.

In summary, therefore, the objections to DPICM provision to Ukraine are militarily dangerous, legally misleading and morally questionable, drawing a false equivalence between Russian and Ukrainian use cases. The use of such weapons by the AFU on their own territory, at their own discretion, against fortifications in open countryside, and against hostile forces who routinely fire Soviet-era cluster munitions and other highly unreliable HE munitions into civilian cities would, therefore, be consistent with the principles of proportionality and discrimination.

DPICM provision will not only increase Ukrainian military effectiveness against dug-in Russian forces, but will also help alleviate Ukrainian and wider NATO ammunition shortfalls and barrel constraints. Since Russia’s current strategy relies on outlasting Western military support capacity, improving the sustainability of Ukraine’s artillery capabilities would also increase the incentive for Russia to end the conflict. Therefore, the US is justified in providing Ukraine with DPICM to help liberate its territory, which is the only assured means of restoring the right of Ukraine’s civilian population to live in peace.

The views expressed in this Commentary are the authors’, and do not represent those of RUSI or any other institution.

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Dr Jack Watling

Senior Research Fellow, Land Warfare

Military Sciences

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Professor Justin Bronk

Senior Research Fellow, Airpower & Technology

Military Sciences

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