“So if you’re trying to block cave entrances or collapse rudimentary tunnel complexes, you might use the MOAB,” said Mark Gunzinger, a former B-52 pilot and senior fellow at the Center for Strategic and Budgetary Assessments. “If you’re trying to penetrate a very hardened, very deep structure, you might want something to penetrate into the target or to a deep enough depth that you cause damage inside. “You have to select the kind of weapon you want to use,” he said. “It’s not always a bigger blast.”