Air Weapons: U.S. Cluster Bombs Get A Reprieve


January 11, 2018: In late 2017 the U.S. decided to reverse a 2008 decision to phase out the use of cluster munitions by 2019. The reason behind this cluster munition ban was the 2010 Convention on Cluster Munitions (CCM). The countries with major stockpiles of cluster bombs, like the United States, Russia and China didn’t sign or ratified the CCM and the American 2008 decision was made to silence critics while keeping their options open. Meanwhile the Americans thought that current cluster munitions could be replaced more effective (precise and reliable) cluster munitions free of the drawbacks that led to the CCM. This turned to be much harder than anticipated because not only are smart munitions much more expensive but also a limited stockpile can be very quickly depleted in conventional conflict.

What happened in Libya during 2011 served as a prime example because after a few weeks of bombing Libya the French and British air forces began running of out of smart bombs. The United States realized that they could face a similar problem in the near future so destroying its stockpile of older cluster bombs (that used unguided sub-munitions) in 2019 would be dangerous American troops. The only cluster munition the Americans had planned to keep after 2019 was the CBU-97/CBU-105 Sensor Fuzed Weapon. That was because this weapon only used guided submunitions that were much less likely to be duds and go off later injuring civilians or friendly troops. The CCM stipulated that the only cluster bomblets allowed were those with a dud rate of one percent or less.

The CCM was created because there were two serious problems with cluster munition. Firstly this kind of weapon covers a large area with smaller munitions that threaten anyone in the area, especially civilians. Secondly clust bomb submunitions are known to have much larger percent of unexploded ordnance than other weapons. These unexploded “bomblets” can cause severe danger (death or disability) to civilians even years after conflicts. Thirdly these leftovers can act as source of explosives for terrorist or rebel groups like it been seen in Afghanistan.

Submunitions were originally designed to have a dud rate similar to the two percent rate for artillery shells. But in practice it was much higher, closer to five percent. Part of reason for this is the lighter weight of submunitions. Shell fuzes detonate a shell when the shell hits the ground. The impact sends a pretty strong message to the fuze that now is the time to do it, and go bang. But submunitions, weighing from a few ounces to a few pounds, can make a soft landing and not generate enough force to activate the fuze. These make even deadlier duds, for the fuze is not defective, just deceived. When enough force is applied to activate the fuze, you have an explosion. The dud rate got higher depending on where the submunitions landed. When there is a lot of snow or mud on the ground, the dud rate was as high as fifteen percent.

When these high dud rate problems were discovered in the early 1980s, several solutions were at hand. More complex, expensive, and reliable fuzes were a possibility. But research showed that to halve the dud rate would double the cost of a submunition. To bring the dud rate down to one percent would quadruple the cost. At the time, submunitions cost about five bucks (in current dollars). In the United States, the largest manufacturer of submunitions, no change was made through the 1980s. To use the more expensive fuzes would mean buying fewer munitions. But the Gulf War of 1991 showed that all those dud submunitions tended to cause a lot of casualties among your own troops. The reason was simple, as you would fire a lot of submunitions at the enemy, and then overrun the enemy positions, your troops would suddenly find themselves amidst all those duds, and friendly casualties were the result.

Israel and Germany, who both manufactured their own submunitions, went for the safer fuze. Better designs brought the cost down and they ended up paying ten to fifteen dollars for each submunition. But they achieved dud rates of less than one percent. The safer fuze was basically a self-destruct device. If the submunition did not explode as it was supposed to, another fuze detonated it within 14-18 seconds.

Even with the better fuzes, submunitions are still more dangerous after the battle than older shells. Fire 10,000 artillery shells (a typical quantity for a battle in an area covering a few square kilometers or so) and you end up with a minimum of 200 dud shells, or as many as 3,000 if you are using old, poorly made stuff. But if you use the most modern submunition equipped shells, you are putting 200,000 or more submunitions into the area and a minimum of 2,000 duds. Fight this battle when there is a lot of snow or mud, with the older fuzes, and you end up with over 50,000 duds. It’s no wonder that most submunition fuzes are now of the more expensive, and more reliable, variety.

Submunitions seemed a good idea at the time, but as with any other new weapon, there were dangers no one anticipated. And thousands of additional dud munitions littering the battlefield turned out to be a rather serious problem no one has a satisfactory solution for yet. But these deadly duds are still insignificant in comparison to the much greater number of older shells and bombs still lying in wait.

One the other hand cluster munitions are often extremely useful because in some cases they are the best option. For example there is hardly better and comparably cheap solution to destroy for example airfield runaway and parked aircrafts. The other targets can be scattered on wide area infantry or formation of armored vehicles/artillery. It should be noted that some modern armored vehicles, like the Leopard 2 tank and Puma IFV are well protected against this threat. The cluster munition is also useful in spreading napalm, mine-laying or even creating blackouts. The last we have seen during Kosovo War in 1999. However the most recent example is the war in Donbas (Ukraine) where Russia and Ukrainian armed forces use it with great efficiency.

The cluster munition for example was used as one of the main ammunition types for M270 MLRS systems as solution for east bloc mechanized and artillery formations during cold war era. The cluster munition successor the Guided Multiple Launch Rocket System (GMLRS) uses warhead filled with a thousands of tungsten pellets packed around an explosive charge. Those penetrators provide the area effect, but are inert so will not result in unexploded ordinance known from classical cluster munition. However their number is still not big enough.

The current cluster munitions inventory is mainly some 30 million cluster bombs. There was an even larger quantity of shells and rockets used by the army and marines that used submunitions but these have been rendered obsolete since 2005 with the introduction of guided shells and rockets. Both of these mean a lot less artillery fire is required to hurt the enemy. But the cluster bombs are another matter and are still in demand even when guided.

The American decision to remove ban for cluster munition is very political decision and although it increases the possibility of civilian casualties it is necessary. The other countries with large stocks of cluster munitions, like Russia and China, have a battlefield advantage over opponents who have, in effect, reduced their capabilities by abandoning cluster munitions. Many European NATO members have destroyed their cluster munition stockpiles. The U.S. decided that the unilateral disarmament imposed by the CCM was wrong in a world where war with aggressors using cluster munitions is a growing possibility. -- Przemysław Juraszek


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