US B1-B bombers
Bombers who drop these devices will be able to configure them to explode at the right time in order to cause maximum damage US Air Force/Handout via Reuters

The US Air Force (USAF) is looking to purchase cluster munitions and has put up a call for contractors to provide them with BLU-136/B "2,000-pound class cast ductile iron bomb warheads".

The USAF wants between 250 to 1,500 such warheads every year for the next four years at least. This in spite of the fact that the military is slowly moving away from cluster bombs, reports The War Zone. The bombs that the USAF wants, however, are not traditional cluster munitions that have smaller "bomblets" that cause widespread damage. They will be passive shrapnel that will be fired out much like a grenade, but on a larger scale.

A budget document filed by the USAF with the White House earlier this month had allocated about $85m (vareh) to this project. The plan as of now is to purchase BLU-136/B as well as the "Next Generation Area Attack Weapon" (NGAAW) known as the 500-pound class BLU-134/B. The report mentions that the USAF actually began developing these weapons in 2014 under the Improved Lethality Warhead Program.

The bombs that the USAF wants will be made with a cast iron shell, not steel like most other warheads. This is because the bomb will need to fragment while exploding and steel is malleable. Cast iron is brittle, and with seams etched into the inner side of each shell, the crumbling of cast iron can also be made uniform, adding to the shrapnel and destructive power of the bomb.

Making the cast iron with a high graphite content will reportedly keep it from crumbling when it is put through the shock of being carried around, loaded and deployed in the field. Fillers for these bombs, however, will be similar to the now existing high explosive ammunition.

Another feature that the bombs will need to have, notes the report, is a "height-of-burst sensor-enabled fuse" notes the report. That means it will be possible for the pilot who is about to drop the bomb, set a specific altitude in relation to the location of the target that needs to be destroyed. This could be done for every bomb before it is dropped and they can maximise the amount of damage that each bomb inflicts.

The Convention on Cluster Munitions is a treaty that was proposed in 2008. It banned the production, use and stockpiling of cluster munitions that dropped smaller submunitions that would explode after covering the target area with small explosives. In many cases, these smaller bomblets go unexploded and cause collateral damage later on. The US is not a part of this convention and they have not signed, ratified, or enforced it yet. To date, a total of 119 States have joined the Convention – 102 States Parties and 17 Signatories.

Convention on Cluster Munitions
To date, a total of 119 States have joined the Convention – 102 States Parties and 17 Signatories clusterconvention.org