America's Giant Bunker-Buster Bomb Ready, But May Not Be Enough To Take On Iran

The arms race has always been defined by the development of stronger offensive and defensive weapons, and in turn, consequent counter-upgrades and advancements.

Today, that race continues, and much like how medieval engineers pondered the tricky task of penetrating a castle's tough ramparts with siege engines and catapults, modern technologists are trying to figure their way around modern-day castles -- hardened concrete bunkers and underground shelters.

America's answer comes in the form of a 30,000 pound, 20-foot long monstrosity of a bomb called the GBU-57 or Massive Ordinance Penetrator (MOP). Intended to tackle hardened facilities in rogue states hiding regime leaders, unconventional weapons, or secret labs, the MOP can penetrate some 200 feet of concrete, obliterating its target with 5,300 pounds of explosives. That sounds like a lot, but the numbers may not look so good for the new American bomb when considering its prime potential target, Iran.

The MOP's payload is many times over what previous munitions in the U.S. could deliver, but it also means the bomb is many times heavier. The country's strategic bombers, like the B-52, B-1, and stealthy B-2 needed to be upgraded to carry the new weapon, and even then, can only take on two at a time. A single bomb costs $15 million, not including additional upgrades, and the U.S. military has only requested 20 (meaning a bill of over 300 million for development and delivery). Refitting bombers to carry the weapon cost another $80 million-plus.

Speaking to the press at the Capitol Hill Club on July 25, Air Force Secretary Michael Donley said the bomb, in development since 2006, was now ready to be used. "If it needed to go today, we would be ready to do that," said Donley. "We continue to do testing on the bomb to refine its capabilities, and that is ongoing. We also have the capability to go with the existing configuration today," he added.

Experts believe that the MOP will offer the U.S. military a better means of removing Iran's nuclear facilities, if the Obama or subsequent administrations ever chose to pursue that option. Previous bombs are thought to be underpowered for the task -- as results from the second Iraq war exposed -- and other large munitions were designed to be used against above-ground enemies. That left only small tactical nuclear weapons, whose use for a strike against Iran would be inconceivable.

But if the MOP is intended for deeply buried nuclear facilities in Iran, perhaps like those such as the uranium enrichment center at Fordo in the center of the country, it will still have a hard task to face. After all, the arms race moves in both directions, and Tehran too has been busy with its own preparations.

As it turns out, Iran happens to be home to some of the of the world's most capable producers of specialty concretes; types of which include those mixed with metallic and mineral particulates and laced with steel reinforcement to improve strength and resilience. Iranian nuclear laboratories may be protected by concrete better able to resist bending, shock, compaction, and tremors.

While the MOP can burrow through 200 feet of normal or "conventional concrete", against "ultra-high performance concrete", which could withstand 10,000 pounds of pressure per square inch, it may only be able to deal with 26 or 27 feet.

An Iranian facility, buried under a large mountain a mile or more below ground, protected by multiple layers of high-strength barriers presents more trouble than one bomb can handle.

The Defense Threat Reduction Agency in the Defense Department, which has developed the MOP and studied how it could be defeated, says tactics is one answer to cracking the conundrum.

Sending multiple bombs one after the other at the same target -- essentially digging a deeper hole -- is one way to deal with the problem (not exactly the most innovative: it's been tried in bombing missions since at least World War II), but no certain guarantee, even with the MOP's satellite-guided precision.

Longer flight duration gives the Iranian military more time to respond to U.S. intruders: in a place like Fordo, well within Iranian airspace, the element of surprise would be lost. The heavy weight of the bomb means fewer bombs per plane, in turn meaning more planes for a bombing operation, exposing even a mission conducted with stealth planes to a greater likelihood of being discovered and intercepted.

Limited numbers of the weapon mean it will need to be used sparingly and carefully. Knocking out a single facility is unattractive, since the country may have redundant locations, which would all need to be destroyed. Returning for a second mission is a poor option, since the enemy would be better prepared.

Other options include using the bomb to attack softer areas of a target rather than trying to destroy it altogether: the entrances and support systems of a facility rather than the very center. Another imperfect solution, since it would simply hinder Iran's nuclear capability, rather than remove it altogether.

Giving the MOP to Israel, which has shown an interest in the new weapon, may not be a solution either. Israel doesn't even have a bomber large enough to carry it.

And all this means that once again no magic bullet, no matter how large and expensive, is yet available for making the Iranian nuclear quandary go away.