Kathmandu: As tensions escalate over Iran’s underground nuclear facilities—particularly the Fordow enrichment site—attention is turning to the United States’ most powerful non-nuclear bomb: the GBU-57A/B Massive Ordnance Penetrator (MOP).
Weighing approximately 13,600 kilograms, this “bunker buster” bomb is designed to penetrate up to 61 meters of reinforced earth and rock before detonating. Built by Boeing, the MOP is widely considered the only conventional weapon capable of reaching and damaging fortified nuclear sites like Fordow, which lies deep beneath a mountain near Qom, about 95 kilometers southwest of Tehran.
How the MOP Works
The MOP is a 6-meter-long precision-guided bomb with a hardened steel casing that allows it to burrow deep underground before exploding. Unlike the MOAB (“Mother of All Bombs”) — which creates surface-level blast effects — the MOP is made specifically to target deeply buried facilities, such as nuclear bunkers and command centers.
Only the U.S. Air Force’s B-2 Spirit stealth bombers, built by Northrop Grumman, are configured to carry the MOP. These bombers can carry up to 18,000 kilograms of payload and are capable of in-flight refueling, giving them a combat range of over 18,500 kilometers—enough to strike any target on Earth.
Why It Matters Now
With Israel openly targeting Iran’s nuclear infrastructure, there’s growing speculation about whether the U.S. would support—or participate in—a strike on Fordow. The site is believed to be protected by at least 80 meters of rock and soil, along with advanced Iranian and Russian air defenses.
Former U.S. President Donald Trump has so far refused to confirm or deny whether the U.S. will participate in military action. However, he has repeatedly called for Iran’s unconditional surrender and warned that “our patience has run out.”
According to Professor Paul Rogers, a retired peace studies expert from the University of Bradford, “Israel does not possess the capability to use the MOP. It lacks both the aircraft and the clearance to do so without U.S. involvement.”
Challenges of Using the MOP
- Limited Inventory: The U.S. is believed to have only 10–20 MOP bombs.
- Delivery Risks: Deploying a B-2 bomber over hostile airspace—protected by Iranian air defense systems—poses a significant threat.
- No Guarantee of Success: Despite being the most powerful weapon of its kind, even the MOP might not fully destroy a deeply buried and heavily fortified site like Fordow.
- Political Fallout: The use of such a weapon could lead to wider regional conflict, drawing in other powers and potentially destabilizing global energy markets.
What Experts Say
- Kelsey Davenport, Director for Nonproliferation Policy at the Arms Control Association, warned that “as long as Fordow remains operational, Iran retains the risk of developing nuclear weapons capabilities in the near future.”
- According to the International Atomic Energy Agency (IAEA), uranium particles enriched to 83.7% purity—close to weapons-grade—were detected at Fordow in March 2023.
- A recent IAEA Board of Governors resolution formally declared that Iran is violating its non-proliferation obligations for the first time in two decades.
Bottom Line
The GBU-57A/B MOP is the best shot the U.S. has at destroying Iran’s most hardened nuclear facilities. But it’s not a silver bullet. “This weapon offers the best chance,” says Professor Rogers, “but whether it will actually work—no one can say for sure.”
As of now, whether the U.S. chooses to deploy it will depend largely on America’s willingness to enter the conflict directly, and as Rogers puts it, “that depends entirely on whether Trump is truly ready to go all-in with Israel.”
