‘Bunker-buster’ MOP and B-2: Why US bomb, stealth bomber were Israel’s best chance at destroying Iran’s Fordo nuclear facility

Israel’s best chance at destroying the facility at Fordo required a never-before-used American bomb — the GBU-57 Massive Ordnance Penetrator, or MOP — which is extremely heavy and can only be dropped using the B-2 Spirit stealth bomber aircraft of the US Air Force. The latest bombing seems to have achieved that target, even though the extent of damage at Fordo is still under speculation, primarily because of the depth of the enrichment site.

The “bunker buster” MOP is designed to attack “deeply-buried facilities and hardened bunkers and tunnels” and is meant to destroy targets in well-protected facilities. Israel, or any country other than the US, does not have any non-nuclear weapon systems that can penetrate a site as deep as Fordo.

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The GBU-57 MOP ‘bunker buster’

The MOP measures about 20.5 feet in length and 31.5 inches in diameter and weighs about 13,000 kgs, according to the US Air Force. The bomb is a “bunker buster”—a type of munition capable of penetrating and hitting targets secured in underground facilities. The MOP is widely believed to be the most powerful non-nuclear weapon.

According to the US Air Force fact sheet, the MOP “is a weapon system designed to accomplish a difficult, complicated mission of reaching and destroying our adversaries’ weapons of mass destruction located in well protected facilities”. It is more powerful than its predecessor, the BLU-109.

It is designed to penetrate up to 60 metres of earth before exploding. The warhead is encased in a special high-performance steel alloy, which is meant to enable it to carry a large explosive payload while maintaining the penetrator case’s integrity during impact, according to an Air Force fact sheet. The Fordo site is about 90 metres in depth. It is not clear how much damage the bombings have done in Fordo.

Satellite images provided by Maxar of the Natanz Enrichment Facility (left) and Fordow Enrichment Facility. (Photos: AP)

The development of the MOP was led by the Air Force Research Laboratory with aerospace and defence company Boeing as the industry partner. The GBU-57 was first tested in 2007, and Boeing got several production contracts for the bomb. At least 20 of these bunker buster bombs were delivered to the US Air Force.

The MOP development followed the US invasion of Iraq in 2003, during which the US Air Force used smaller and older bunker buster bombs. However, those weapons were unable to penetrate as deeply as needed and resulted in limited damage. The US wanted a more powerful non-nuclear weapon, which led to its Defense Threat Reduction Agency (DTRA) launching the MOP project. The latest airstrikes in Iran mark the first known use of the MOP in combat.

The B-2 Spirit stealth bomber

Without resorting to use of nuclear weapons, the MOP was believed to be the only bomb that could have taken out a site like Fordo. Speculation was rife that Israel was pressing the US to use the MOP, which has now been confirmed with the American strikes. The only aircraft that could have delivered the payload is the B-2 Spirit stealth bomber, which can carry and deploy two MOPs.

The B-2 is a heavy strategic bomber with Northrop Grumman as the prime contractor and Boeing, Hughes Radar Systems, General Electric, and Vought Aircraft Industries as key members of the aircraft contractor team. The B-2’s first flight was in July of 1989, but it entered service with its initial operating capability in 1997. A total of 21 of these stealth bombers, each with a price tag of almost $1.2 billion, were built. The US currently has an operational B-2 fleet of 19 aircraft.

The B-2 was first deployed in the Kosovo War in 1999. Later deployments included missions in Iraq, Afghanistan, Libya, Yemen, and now Iran. It’s extremely long range capability allow it to fly across continents from its base, complete the mission, and fly back. Its unrefueled range is approximately 6,000 nautical miles, 9,600 kilometers. With one mid-air refueling, the B-2 can fly for over 19,000 km.

Produced by Northrop Grumman, the B-2 Spirit comes with a hefty price tag of approximately $2.1 billion per unit. (Photo: Northrop Grumman)

“The B-2 provides the penetrating flexibility and effectiveness inherent in manned bombers. Its low-observable, or ‘stealth’, characteristics give it the unique ability to penetrate an enemy’s most sophisticated defenses and threaten its most valued, and heavily defended, targets. Its capability to penetrate air defenses and threaten effective retaliation provides a strong, effective deterrent and combat force well into the 21st century,” according to the US Air Force.

In fighter aircraft, stealth refers to the ability to evade air defenses and radars during missions. According to the US Air Force, the B-2’s low observability—stealth qualities—are derived from a combination of reduced infrared, acoustic, electromagnetic, visual and radar signatures. These reduced signatures make it difficult for the sophisticated defensive systems to detect, track, and target the B-2. The B-2’s composite materials, special coatings, and a standout flying-wing design contribute to its “stealthiness”, even as many other aspects of the low-observability remain classified.

The B-2 was responsible for destroying 33 per cent of all Serbian targets in the first eight weeks, by flying nonstop to Kosovo from its home base in Missouri and back, as per the US Air Force. In the Afghanistan War, the B-2 flew one of its longest missions to Afghanistan and back. In Operation Iraqi Freedom, the B-2 flew 22 sorties from a forward operating location and another 27 sorties from its base in Missouri, releasing more than 1.5 million pounds of munitions.