The "Mother of All Bombs" Explained

My friend Michael Schmitt, a former Air Force JAG officer now on the faculty of the Naval War College, is my go-to academic on all Law of Armed Conflict issues.  For those troubled by the use of a 22,000 pound bomb known as the Massive Ordnance Air Blast Weapon ("MOAB") in Afghanistan, Alongh with Lt. Commnander Peter Barker, Mike offers a very useful primer at Just Security:

The MOAB is huge by conventional bomb standards. Weighing in at approximately 11 tons, it contains 18,700 lbs. of H-6 explosive, which was originally developed for underwater explosions due to its low sensitivity to shock and stable storage characteristics.  This is the largest quantity of explosive in any non-nuclear weapon in the US inventory (although there are larger weapons by weight, they contain less explosive due to having heavier casings designed to penetrate targets).  By way of comparison, the frequently-used Joint Direct Attack Munition (JDAM) comes in at launch weights of between roughly 500 lbs. and 2000 lbs.

.  .  .

The MOAB can be viewed as a weapon with value at the tactical, operational, and strategic levels of warfare.  It is tactical in the sense that the weapon is especially useful against certain targets, such as caves and tunnel systems. General John Nicholson, Commander of U.S. Forces Afghanistan, noted that the MOAB strike served tactical purposes: “As ISIS-K’s losses have mounted, they are using [improvised bombs], bunkers and tunnels to thicken their defense…. This is the right munition to reduce these obstacles and maintain the momentum of our offensive against ISIS-K.” He added, “It was the right time to use it tactically against the right target on the battlefield,”

Beyond tactical use, the MOAB could serve to force the enemy to discard particular tactics to achieve operational level of war objectives. And at the strategic level, it is useful in signaling resolve and other strategic messaging. However, in light of its cost ($16 million each) and size, it is unlikely to be used with any frequency.

Despite the attention it has drawn, the MOAB presents no unique issues or challenges for international humanitarian law (IHL).   As a guided weapon, it does not run afoul of the prohibition on weapons that are by nature incapable of being directed at lawful military objectives.  On the contrary, the fact that it is a precision munition using GPS for guidance cuts the other way.  Nor is the MOAB a weapon that causes superfluous injury or unnecessary suffering, for its effects on combatants are basically the same as those of other blast weapons that rely upon the creation of a pressure wave to injure or kill.  It appears clear that the MOAB is not a weapon that is unlawful per se.

Read it all here.  As Mike and Commander Barker explain, while the MOAB is not unlawful per se, given its power, its use in a particular circumstance could violate the law of armed conflict.  For example, if it were used in a setting where many civilian casualties would be expected, its use might be unlawful.  In the use last week, however, it was used in a remote location with no civilians present.