Today, for the first time, the Massive Ordinance Air Blast, or the Mother Of All Bombs, was dropped by the U.S. armed forces, used against an ISIS target in Afghanistan. But what is the MOAB? Why have we never dropped one before? And will there be more drops?
The MOAB is formally known as GBU-43/B Massive Ordinance Air Blast, a giant 21,600 pound bombshell filled with Composition H-6, a military explosive that mixes TNT, RDX explosive, nitrocelluose explosive, and a few other ingredients to make an explosive roughly one and a third times as powerful as TNT. The MOAB has an explosive force of 11 tons of TNT and has a one-mile blast radius. It’s so large it can’t be “dropped” in the way you imagine a bomb is dropped; instead it has to be shoved out of a plane at high altitude and parachuted towards its target with satellite guidance.
Despite that, though, the MOAB isn’t intended to hit the ground and explode. Instead, it’s what’s called a thermobaric weapon. It uses oxygen from the surrounding air to set off the blast, and the result is an explosive with an exceptionally long blast wave. It’s sometimes also called a “vacuum bomb” because the reaction sucks all the oxygen out of the surrounding air. If you’re inside a building, the blast wave “bounces” and is even more amplified, killing everyone inside and destroying the structure. A Defense Department study from 1993, obtained by Human Rights Watch, paints an ugly picture of this bomb going off:
What kills is the pressure wave, and more importantly, the subsequent rarefaction [vacuum], which ruptures the lungs…. If the fuel deflagrates but does not detonate, victims will be severely burned and will probably also inhale the burning fuel. Since the most common FAE fuels, ethylene oxide and propylene oxide, are highly toxic, undetonated FAE should prove as lethal to personnel caught within the cloud as most chemical agents.
Needless to say, the use of thermobaric weapons is controversial. The Syrian government has been accused of dropping them indiscriminately. But they are accepted tools of war, and the U.S. military has made extensive use of smaller weapons like the XM1060 40-mm grenade and the AGM-114N Hellfire II missile. The XM1060 is so powerful it was reported that just one could destroy a one-story building from 100 yards.
It’s still unclear how much damage was done, or whether there will be future blasts. Even the military has, historically, been reluctant to use the MOAB; even in 2003, when one was shipped to the Persian Gulf, it was seen more as an intimidation tool than an effective munition. While it’s not entirely certain just how many MOABs there are, only a small number of them have been reported to ever be manufactured. So it’s unlikely this will become a common feature of modern warfare and frankly, considering the effects of the bomb, that may be for the best.