Evan Horowitz | Quick Study

When is it OK to drop a bomb this size?

The MOAB bomb was tested at Eglin Air Force Base, Fla., in 2003.
The MOAB bomb was tested at Eglin Air Force Base, Fla., in 2003. (Photo by USAF via Getty Images)

On Thursday, the US military made its first battlefield use of a weapon whose name bespeaks its power: MOAB, which unofficially stands for “mother of all bombs.” Its target: a cave and tunnel complex controlled by an ISIS-affiliated group in Afghanistan.

The MOAB is one of the biggest non-nuclear weapons in the US arsenal, which also gives it a unique psychological power, garnering massive media attention and conveying a clear message about the full extent of US air power.

Note, though, that the MOAB has actually been around since 2003. There’s a reason it’s never been used: the bigger the bomb, the harder it is to drop.


That’s because even war has its rules, established by longstanding practice and codified in internationally-recognized treaties like the Geneva Conventions.

Break them — as Assad has done with his use of chemical weapons — and you become a war criminal. To stay within the lines of acceptable warcraft, you need to ensure that:

1) Your actions are necessary to your goal

2) You target soldiers, not civilians

3) You don’t cause undue or unnecessary suffering

4) Any damage to people and property is proportional to the expected gains of your attack

That last one is the key limitation when it comes to dropping large bombs. Weapons as powerful as the MOAB can create damage across a relatively wide area, which makes it harder to ensure that the costs will be proportional to the gains. Urban use is effectively ruled out, as is any enemy position ringed by civilians.

The only really appropriate target would be a remote facility. In that sense, Thursday’s attack would seem to meet the conditions, seeing as it focused on a fortified encampment in remote Afghanistan.

Beyond the legal concerns, though, there may be another reason the Trump administration reached for the MOAB in this particular instance: propoganda value.


Massive weapons like this one are especially useful if what you’re looking for is shock and awe — a display of raw military power. Indeed, that seems to be one of the reasons the US military developed MOAB in 2003. At the time, defense officials acknowledged that the MOAB was partly a “psychological” weapon, meant to demonstrate the overwhelming US advantage in military hardware during the Iraq War.

Fifteen years later, this same psychological aspect may again be paramount, a way for the Trump administration to send a message to ISIS and its allies: we’re coming for you with everything we’ve got.

There’s at least one clue to suggest such a motivation. The target selected for this first MOAB strike was in the same part of Afghanistan where a US special forces soldier was killed while involved in anti-ISIS operations last week.

Evan Horowitz digs through data to find information that illuminates the policy issues facing Massachusetts and the U.S. He can be reached at Follow him on Twitter @GlobeHorowitz