No matter how well prepared a military is, it’s never easy to shift direction rapidly to respond to new threats. One U.S. Air Force briefing suggests Pentagon’s rush to counter ISIS in Iraq and Syria sent the service scrambling to find the right mix of tactics and weapons, with nearly 20 percent of its bombs failing to achieve the desired effect within the first four months of the bombing campaign and potentially contributing to an ongoing shortfall of certain bombs and missiles. On Aug. 7, 2014, the United States kicks off air strikes against the brutal terrorists in Iraq, beginning attacks on its members in neighboring Syria the following month. But between August and November 2014, the Air Force saw between 11 and 19 percent of weapons either not have the intended effect or not detonate entirely, according to a briefing Air Force Major Brian Baker gave at the National Defense Industry Association’s Precision Strike Annual Review in March 2017. At the time, Baker was one of the American representatives at the multi-national Air and Space Interoperability Council, which included individuals from all of the so-called “Five Eyes” countries – the United States, Australia, Canada, New Zealand, and the United Kingdom.

The main reason for this was that the Air Force had initially shifted forces from Afghanistan, who had been primarily providing close air support and other counter-insurgency type missions, to the new fight in Iraq, he explained. By comparison, the situation in Iraq and Syria was “more similar to air interdiction – disguised as CAS [close air support].” In general, CAS is supposed to describe strikes on targets that are actively engaged with friendly forces on the ground. Interdiction refers to attacks on the enemy before they get to an actual battle. Baker’s description matches up with what a public affairs officer for Combined Joint Task Force – Operation Inherent Resolve told me about aerial missions against ISIS all the way back in January 2015. At that time, there was some confusion in the official categorization of the missions.

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Iraqi or Kurdish troops and vetted Syrian rebels only needed to be “in proximity” to ISIS fighters – sometimes miles away – for the Air Force to count the strike CAS, the official acknowledged. “It is sometimes the case that sorties tasked for CAS may wind up supporting strikes that look more like interdiction, or vice versa.” Though perhaps a pedantic difference to many people, this confusion in roles had a direct impact on the kinds of weapons Air Force multi-role fighters, bombers, ground attack aircraft, and drones carried on each sortie. In his presentation, Baker identified three particular systems were major contributors to the early problems, the GBU-38(V)4/B and 5/B Joint Direct Attack Munition (JDAM) bombs and the DSU-33/B proximity sensor.

USAF An full load of GBU-38/Bs under the wing of a B-52 bomber.

The two JDAM types are a GPS guidance kit attached to the BLU-126/B Low Collateral Damage Bomb (LCDB) and BLU-129/B Very Low Collateral Damage Bomb (VLCDB) respectively. These 500-pound class warheads both cause damage within a relatively small blast radius compared to full-power weapons. The DSU-33/B triggers the bomb’s fuze to air burst above the targets, showering them in shrapnel. Combining the DSU-33 and either the LCDB or VLCDB creates a munition that is precise, deadly against enemy personnel who are either entirely exposed or with no cover above, and safe enough for pilots to drop in relative proximity to friendly forces. In short, it’s a great option for supporting troops on the ground in the midst of a protracted firefight who might desperately need air support.

USAF Airmen at Al Udeid Air Base in Qatar assemble GBU-31/B JDAMs.