The U.S. Air Force is developing a terrifying new weapon to replace cluster bombs.

Instead of scattering thousands of tiny bomblets over a target, the service plans to rain down iron fragments … to essentially achieve the same effect.

During the opening phase of Operation Iraqi Freedom in 2003, the United States and coalition forces dropped thousands of cluster bombs on targets including missile and radar sites, Iraqi aircraft, armored vehicles, artillery batteries and troops.

While effective, the cluster bombs often left behind thousands unexploded bomblets that killed many civilians.

Responding to international pressure, in 2008 then-Secretary of Defense Robert Gates ordered the services to phase out the procurement of cluster bombs—and stop using them completely after 2018.

In response to the looming prohibition on cluster bombs, in 2011 the Air Force began exploring new munition concepts to comply with the new policy while achieving the same “area attack” effects.

Fast forward to today, and the Air Force believes it has found a near-term solution—iron warheads.

By producing a general purpose bomb with a unitary “cast ductile iron warhead” and reconfiguring the burst height and fuze location, the service believes the weapon will be an effective stopgap solution as the ban on cluster munitions approaches.

Gates’ 2008 memorandum specifically bans cluster bombs that result in more than one percent unexploded ordnance. However, Gates’ 2008 memorandum acknowledges the military usefulness of cluster bombs, and the Pentagon has no plans to go to war with one hand tied behind its back.

The United States is not a signatory to the 2008 multinational convention on cluster munitions.

An airman loads a Joint Direct Attack Munition bomb (U.S. Air Force)

“Cluster munitions are legitimate weapons with clear military utility,” Gates’ memorandum states. “There remains a military requirement to engage area targets that include massed formations of enemy forces, individual targets dispersed over a defined area, targets whose precise locations are not known and time-sensitive or moving targets.”

The Air Force began seriously exploring a follow-on cluster munition in 2011 by calling for white papers from industry. Several munitions concepts were explored, from new types cluster munitions to multiple small weapons, unitary warheads and even “non-kinetic” options.

Later efforts have involved running advanced computer simulations to characterize different weapon effects, and the Air Force confirmed this month that so-called “cast ductile iron warheads” represent the best way forward.

In September, the service posted a notice on the government’s procurement Website calling for vendors to produce 50 to 100 of these iron warheads, which must be similar in size and shape to the 500-pound BLU-111 penetrator bomb. But unlike the penetrator bomb, the casing will be iron, not forged steel.

A spokesman for the Air Force Life Cycle Management Center—the organization responsible for Air Force weapons procurement—said the iron warhead design will satisfy the requirement for cluster-munition-type effects.

“The construction of cast ductile iron warheads has been accomplished before, BLU-111D/B, so this solution is viewed as a relatively low-risk endeavor that will enable an area-attack capability by the end of 2018 in compliance with DOD policy,” the spokesman said.

“The Air Force is examining both near term and long term options to replace cluster munitions. The near term solution improves the area attack capability of existing unitary warheads by changing the case material,” the spokesman explained.

“Longer term improvements may incorporate pre-formed fragments, improvements in height-of-burst fuzing, and selectable fuzing locations to produce different weapon effects. These improvements will most likely add capability to existing weapons rather than indicate a new class of weapon.”

Throughout this year the armaments directorate at Eglin Air Force Base in Florida has been conducting a series of computer simulations to characterize and test blast fragmentation of iron warhead design. The service said these efforts explored different fragment sized and material compositions, and a number of “arena tests” occurred—possibly indicating live-fire experiments.

Weapons researchers also examined different burst heights and fuze locations, altering the fragmentation and blast area.

The Air Force confirmed that through 2015 there will be further computer simulation testing and a formal acquisition strategy for iron warheads will be established. The first 50 to 100 iron warheads the service wants to by will be compatible with the GBU-38 and GBU-54 bombs, according to the Air Force’s market research document.

The addition of iron unitary warheads to the Air Force’s weapons inventory will surely lead to new concepts of operation. Because the bombs won’t leave scattered unexploded ordnance, there should be less chance of unintended civilian deaths.

Notice we said less chance. Not no chance.