What is the ‘Mother of All Bombs’ US could use in Iran?

The United States has developed plans to strike Iran with the largest non-nuclear bomb in its military arsenal on Iran’s energy infrastructure and nuclear sites if President Donald Trump orders renewed combat operations, according to US officials cited by CNN.

Deploying the GBU-43/B Massive Ordnance Air Blast Bomb (MOAB), nicknamed the “mother of all bombs”, could significantly escalate the ongoing conflict at a time when fighting has lulled, experts say.

Concerns are also being raised, including within the Trump administration itself, over what such a move would even achieve. Officials familiar with military planning discussions told US news outlet CNN and Al Jazeera that deploying the MOAB would be unlikely to help the US achieve its stated strategic goals, including to destroy Iran’s nuclear capabilities.

Brussels-based military expert Elijah Magnier told Al Jazeera that using the MOAB would not even guarantee the destruction of Iran’s deeply buried underground nuclear installations and that such a strike would likely amount to little more than “political theatre”.

Here’s what we know:

What is the MOAB?

The GBU-43/B Massive Ordnance Air Blast Bomb (MOAB) is a massive munition containing about 8,500kg (18,000 pounds or 8.5 tonnes) of high explosives. It weighs 9,800kg (21,605 pounds or nearly 10 tonnes) – about the same as four saloon cars – and is as long as a small yacht at just over 9 metres (about 30 feet).

The MOAB is typically deployed from the Lockheed C-130 Hercules cargo aircraft because it cannot fit in a stealth bomber.

The bomb, which was first manufactured between 2002 and 2003, has undergone 12 detonation tests.

Its name is a reference to former Iraqi President Saddam Hussein’s comments during the 1991 Gulf War when he invoked the “mother of all battles”.

The US has only deployed the MOAB once before – during its 2017 attacks on an Islamic State Khorasan Province (ISKP) cave and tunnel complex in Afghanistan. Afghan authorities claimed that while 94 Islamic State-Khorasan Province (ISKP) fighters were killed in the blast, no civilians were hurt. However, there were unconfirmed, local reports of civilian casualties and many homes were destroyed.

What kind of damage can it cause?

Designed to explode a few feet above the ground, the MOAB sends out lethal waves of fire when it detonates, blasting away buildings, cave openings and other hard-surface structures.

“Its purpose is to generate an exceptionally powerful blast across a surface area,” Magnier said.

Military expert Colonel Nidal Abu Zeid told Al Jazeera the bomb does not require impact in order to detonate and that its massive blast will destroy everything above ground within a 1km (0.6-mile) radius.

It is likely that the US would aim to use the high-explosive MOAB to completely destroy Iran’s ground-force positions above ground, and to reach its underground facilities, including Pickaxe Mountain, which Trump has previously threatened to attack, Abu Zeid said.

However, Magnier said the bomb’s radius and level of destruction would depend greatly on the terrain it is used within and how populated the area is. He added that it may not be particularly effective against targets buried deep underground.

Some of Iran’s nuclear sites which the US may wish to target, such as the Fordow complex and an under-construction site at the Pickaxe Mountain, are heavily fortified and deeply buried.

“Its large explosive charge can produce devastating blast effects against exposed personnel, equipment and vulnerable structures,” Magnier said. “The Afghanistan operation demonstrates its intended application against a cave-and-tunnel position; it does not demonstrate an ability to destroy every kind of underground installation.”

While its blast can reach underground, the MOAB is not especially designed to punch through deep concrete or mountain rock in the way that a “bunker buster” bomb is. The US military’s most powerful bunker buster is the GBU-57 Massive Ordnance Penetrator. Weighing about 30,000 pounds (13,600kg), including a 2,700kg (6,000 pound) warhead, this precision-guided bomb is made of high-strength steel and built to penetrate up to 200 feet (61 metres) underground before exploding.

Would the US really use an MOAB?

It already has done – in Afghanistan in 2017.

However, besides not being guaranteed to hit underground targets effectively, Magnier told Al Jazeera it could be difficult to deploy the necessary aircraft in the regions of Iran where nuclear sites are located. Stealth bombers which are better suited to this terrain are not able to carry this size of bomb.

Using the bomb could also destroy infrastructure without inducing Iran to make any concessions, he added, noting that its deployment would risk turning “a spectacular event” into one that ultimately delivers few political results for Washington.

“The question I would put to any commander advocating its use is straightforward: What will this weapon accomplish that another available weapon cannot, and how will that result advance an achievable political settlement?,” Magnier said.

“If the answer centres on the spectacle of the explosion, the proposal is stronger as political theatre than as military strategy,” he added.

CNN reported that Trump, in private discussions, has been seeking a “definitive” end to the war that will prove Washington has been undefeated.

How might Iran respond?

A MOAB strike would likely prompt a major reaction from Iran, experts say, warning that Tehran could even invade its neighbours who host US military assets in response.

Iranian security officials have for months made comments regarding a possible invasion of countries like Kuwait to capture US troops and force Washington to surrender.

In May, during a pause in hostilities, Kuwait alleged that sailors from Iran’s Islamic Revolutionary Guard Corps (IRGC) infiltrated its Bubiyan Island, leading to an exchange of fire between Iranian and Kuwaiti forces. One Kuwaiti was injured and four Iranian soldiers were captured.

Iran denied that it had invaded the island and said the troops’ navigation system had malfunctioned.

On Tuesday, IRGC security adviser Mohammad Reza Naghdi warned that Iran could capture troops if Washington were to launch ground attacks, although military experts have long dismissed Trump’s earlier threats of an invasion due to Iran’s mountainous terrain.

“If the United States launches a ground attack, so many of its troops will be captured that it will be forced to raise the white flag,” he said.

Experts say Iran has been preparing for another round of war by stockpiling weapons, fortifying key nuclear and defence locations, and rallying its supporters.

In a television broadcast on Sunday, National Security Council chief Mohsen Rezaei threatened that Iran would attack regional digital infrastructure, including communication cables, data centres and artificial intelligence facilities in the United Arab Emirates and others, if American strikes resume.