On Thursday, U.S. forces detonated the most powerful conventional weapon in the U.S. arsenal, the Massive Ordnance Air-burst Bomb or MOAB, against an ISIS tunnel complex in Afghanistan’s Nangahar Province which is just along that country’s northeast border with Pakistan. The MOAB first entered the US arsenal in 2003 during the lead up to the invasion of Iraq. Its recent employment is the first time it has been used in a combat situation.
Weighing 21,000 pounds, the satellite-guided MOAB is packed with some 18,000 pounds of a gelled slurry of ammonium nitrate and powdered aluminum detonated by a highly explosive booster. The MOAB delivery package consists of an inertial guidance system, a global-positioning system, and fins and wings for course adjustment, making it extremely accurate. Given its massive size, the MOAB is dropped by parachute from a C-130 transport plane before the satellite-guidance system takes over.
The MOAB is a follow-on to a weapon designed to clear helicopter landing zones in Vietnam, the BLU-82 “Daisy Cutter,” a 15,000 pound fuel air explosive device. The BLU-82 was also employed in the 1991 Gulf War and more recently in Afghanistan, where along with the BLU-118/B thermobaric weapon, it was used against al Qaeda troops in fortified caves.
Military officers contemplated employing the MOAB during the Iraq War. Indeed, as the war approached, the Department of Defense made no effort to keep the effects of the MOAB secret. This lack of secrecy suggested that the weapon had a distinct psychological objective: the potential destruction of an Iraqi Republican Guard unit as an incentive to others to surrender.
A fuel-air explosion of the magnitude of the MOAB generates blast and overpressures similar to a small nuclear weapon, minus the radiation. But the fact that so much of the Iraq War took place in populated areas precluded the use of the MOAB. But the isolated area in which the ISIS compound was located before Thursday made it a perfect target for the weapon.
A few observations: first, the employment of the MOAB seems to be the fruit of President Trump’s decision to return to the idea that the military “on the ground” ought to have the authority to make tactical decisions. Reports suggest that the decision to use the MOAB came from Central Command, not the White House. This devolution of decision making is a welcome change. During the Obama years, the rules of engagement (ROE) were so restrictive that U.S. casualties were higher than necessary. In addition, opportunities to inflict damage on the enemy were often lost.
Second, although the purpose of the strike was tactical—the destruction of the ISIS complex—the use of the MOAB also sent a clear message to the mullahs in Iran, to Assad in Syria (and by extension to one of his sponsors, Putin), and to North Korea. Although the use of the MOAB is limited in many potential instances due to the possibility of civilian casualties, the United States has also developed a “bunker buster” version of the MOAB: the GBU-57 A/B Massive Ordnance Penetrator (MOP), a weapon designed to destroy deeply buried hardened targets.
The MOP is a 30,000 pound direct-strike hard-target weapon (DSHTW) featuring 5.300 pounds of high explosive enclosed in a cobalt-alloy bomb body. This configuration enables it to penetrate to depths of up to 100 feet underground before detonating.
So what does all of this mean? Does the Syria strike and the employment of the MOAB in Afghanistan indicate that President Trump is eager to broaden foreign adventurism? Not necessarily. More likely, President Trump is signaling to our adversaries that future aggression will not be cost free.
This is the essence of deterrence, a concept that has atrophied since the end of the Cold War and the perception that nuclear weapons are less important than they once were. But while deterrence was central to our thinking about nuclear weapons, the concept has broader application.
For deterrence to work, three conditions must be met. First, the party that seeks to deter an adversary must have the capability to do what it threatens to do. Second, the deterring party must demonstrate the will to follow through on a threat. Finally, there must be an element of uncertainty at work.
Our adversaries became more aggressive during the Obama years because of the absence of the last two factors. The Obama administration made it clear that it lacked the will to carry through on threats, e.g. Obama’s “red line” in Syria. Obama’s predictable behavior also lessened our adversaries’ uncertainty.
Trump’s actions have restored the missing two elements (our will to use force and the enemy’s uncertainty) to the concept of deterrence. Even though the employment of the MOAB was primarily a tactical decision, in the long run it has a strategic effect by putting adversaries on notice that the leadership of the United States possesses the will to act. Our adversaries also face a level of uncertainty that they did not face with Obama. Contrary to the fears of some Trump supporters, the new circumstances actually lessen the likelihood of US involvement in conflict abroad.