It’s no surprise that the Iranian nuclear program talks are shaky; Guy has detailed the long, tedious, and sometime frustrating timeline of these diplomatic talks. So, given that we’re approaching the June 30^th deadline–with the Supreme Leader Ayatollah Khamenei issuing demands that the U.S. could never agree to–what’s the military option, if there is one? The answer is MOP, or “Massive Ordnance Penetrator;” the largest and most powerful nonnuclear bomb we have in our arsenal (via Politico):

…at least three times in the past year, a B-2 stealth bomber has taken off from an Air Force base in Missouri and headed west to the White Sands Missile Range in New Mexico. For these missions, the $2 billion plane was outfitted with one of the world’s largest bombs. It is a cylinder of special high-performance steel, 20 feet long and weighing 15 tons. When dropped from an altitude likely above 20,000 feet, the bomb would have approached supersonic speed before striking a mock target in the desert, smashing through rock and burrowing deep into the ground before its 6,000 pounds of high explosives detonated with devastating force.

“It boggles the mind,” says one former Pentagon official who has watched video of the tests.

…

Iran’s facility, known as Fordow, houses 3,000 centrifuges that can enrich uranium to a purity suitable for nuclear weapons. Fordow is not Iran’s only enrichment facility, or even its largest. But it is the best protected. And it would be all Iran needs to develop a nuclear weapon.

The mock desert target was almost certainly meant to simulate Fordow.

When Obama officials say that “all options are on the table” to stop Iran from getting a nuke, they are in effect speaking in code about the MOP. The MOP is what Secretary of State John Kerry was clearly referring to when he recently told Israeli TV that the U.S. has “designed and deployed a weapon that has the ability to deal with Iran’s nuclear program.” When CNN recently put the question directly — can the MOP destroy Fordow? — to Secretary of Defense Ashton Carter, he was succinct: “Yes. That’s what it was designed to do.”

So, we have something on the military menu to deal with Iran in case things talks collapse, but will Obama actually use this option? Some think it’s probably best for his successor, preferably a Republican one. Yet, if the president–either Obama (let’s say he approves this for argument’s sake) or his successor–green lights this operation, it will take multiple runs to ensure that the centrifuges are destroyed at Fordow. Moreover, the Iranians know we have this capability, and might just build new nuclear sites deeper into the mountains. If that’s the case, then the United States will just build bigger, more effective bunker-busting bombs:

If the order came from the White House, it would most likely summon Whiteman Air Force Base to action. Crews there would load the internal weapons bays of several B-2 bombers with MOPs. The giant stealth planes would then depart for their nearly 7,000-mile flight to mountainous western Iran. By the time the planes actually took off, the mission would likely be old hat to the pilots: A massive flight simulator at Whiteman includes a full-size replica of a B-2 cockpit mounted on hydraulics to mimic flight motion. Its realistic wraparound cockpit computer screen can be preloaded with highly detailed graphics showing the topography and target areas the flight crew would see during the flight, allowing them to practice the bomb run—or even the entire flight—under different weather conditions or times of day.

Once over Fordow at an altitude of 20,000 feet or more, the bombers would release their massive payload. As the enormous bombs fell, they would accelerate to phenomenal speeds of perhaps 700 miles per hour or more. Guided by satellite positioning, flexible tailfins would steer the MOP to a very precise impact point likely identified by the UFAC. The bomb would strike the rock with the tip of its sharply pointed nose. Its supremely reinforced casing would protect the fuse and explosives inside from the initial impact. In effect, a 15-ton, 20-foot nail would pound into the earth at the speed of sound.

Violent as that impact may be, it would hardly be enough to get the job done. The goal is for the MOP to drill dozens or even hundreds of feet through rock before exploding. That is made possible by smart fuses, whose blasts are triggered not by impact but by conditions like time, depth, or the presence of a void indicating that the bomb has broken through an interior ceiling.

Fordow is buried deep enough that a single MOP probably would not penetrate to the centrifuge hall deep inside. That’s why several bombers would likely drop their ordnance in succession, gradually smashing a tunnel of devastation towards mountain’s soft interior. GPS precision would enable several MOPS to be landed on virtually the exact same spot in rapid succession: the most powerful jackhammer in history.

Politico also added that the capabilities of this weapon system have been constantly upgraded and refined in its ten-year lifespan. In 2012, the U.S. military didn’t have the ability to destroy an installation in Fordow; we’ve spent $100 million to retrofit our fleet of B-2 bombers to carry the 30,000+ bomb; new smart fuses set to trigger the explosives based on time and depth; and new GPS countermeasure to block Iranian jamming systems.

Here’s the Fox News and CNN reports on MOP from 2012.