It is too big for a bomber. The GBU-43/B Massive Ordnance Air Blast, better known by its unofficial name, the “Mother of All Bombs”, weighs nearly ten tonnes and is pulled out of the rear cargo door of a C-130 by a parachute. It has been used in combat exactly once, in Afghanistan in April 2017. In October 2026 it was back in the news, when CNN reported, citing US officials, that plans had been drawn up to use it against Iran.

Here is what the MOAB actually is, how it works, and why it is not the weapon many people think it is.

From Daisy Cutter to MOAB

The MOAB grew out of an older weapon. In late 2001, US forces in Afghanistan dropped BLU-82 “Daisy Cutter” bombs, 15,000-lb weapons originally used in Vietnam to clear helicopter landing zones in the jungle. They were judged effective, not least as a weapon of intimidation. The Air Force Research Laboratory at Eglin Air Force Base in Florida was asked for something bigger and more accurate, and Al Weimorts designed it in 2002. Production followed at the McAlester Army Ammunition Plant in Oklahoma.

The official name, Massive Ordnance Air Blast, was chosen so that the acronym spelled MOAB. The nickname followed almost immediately, echoing Saddam Hussein’s “mother of all battles” from the 1991 Gulf War.

The 2003 Tests

The first MOAB was dropped on 11 March 2003 on Range 70 at Eglin, nine days before the invasion of Iraq. The timing was widely read as a message to Saddam Hussein’s forces. That first test bomb was filled with tritonal; production weapons use H-6. Reports at the time said the mushroom cloud could be seen about 20 miles away. A second test followed on 21 November 2003.

The 2003 MOAB test at Eglin, from the BBC News archive.

How It Works

The MOAB is a blast weapon, not a penetrator. It sits on a cradle on an airdrop platform inside an MC-130. Over the release point, a drogue parachute pulls the platform out of the cargo door; the bomb then separates and falls free, steered to its target by GPS guidance and four large lattice-shaped grid fins at the tail. It detonates just above the ground.

Most of its weight is explosive. The thin aluminium casing weighs only about 2,900 lb, leaving some 18,700 lb of H-6, an aluminised high explosive. The result is a huge, long-lasting pressure wave that spreads across the surface and into confined spaces such as valleys, caves and tunnel entrances. That is exactly what it was designed for: soft and medium targets, troops and equipment over a wide area, and terrain that funnels the blast.

To put the yield in context: about 11 tons of TNT is enormous for a single conventional bomb, but tiny compared with a nuclear weapon. The Hiroshima bomb released the equivalent of roughly 15,000 tons. And a typical B-52 Arc Light raid in Vietnam delivered as much explosive as 10 to 17 MOABs, spread over a much larger area.

Achin, April 2017

The MOAB’s only combat use came at about 7:32 p.m. local time on 13 April 2017. An MC-130 released one over a tunnel and cave complex used by the Islamic State’s Afghan branch, Islamic State–Khorasan Province, in Achin district, Nangarhar province, close to the Pakistani border. The tunnels had originally been built in the 1980s for the mujahideen fighting the Soviet occupation. General John Nicholson, the US commander in Afghanistan, approved the strike. Days earlier, Army Special Forces Staff Sergeant Mark De Alencar had been killed in fighting in the same province.

Footage of the April 2017 strike released by the US military, via PBS NewsHour.

Casualty figures remain uncertain. Afghan officials first said 36 militants were killed, then raised the figure to more than 90. Islamic State denied it had lost anyone, and a local member of parliament reported that residents said a teacher and his young son were killed. The Afghan army said there were no civilian casualties. Reporters who later reached the area found trees still standing about 100 metres from the impact point, and many similar caves nearby. Fighting in the valley continued.

What the MOAB Cannot Do

The MOAB is often confused with the US Air Force’s other giant bomb, the 30,000-lb GBU-57 Massive Ordnance Penetrator. They are opposites. The MOP is heavy and narrow, with a thick steel case built to punch through rock and concrete before exploding; it was used against Iran’s Fordow enrichment site in June 2025, and we covered later strikes in B-2s Drop 30,000-lb Bunker Busters. The MOAB has a thin case and explodes above the surface. Against a facility buried deep underground, it would do little more than damage what is on top.

That is why the October 2026 reports about Iran drew sceptical responses. According to the CNN reporting, plans covered Iranian energy infrastructure and nuclear sites if President Trump ordered renewed strikes, but officials themselves doubted the MOAB would help achieve US goals such as destroying Iran’s nuclear capabilities. Military analysts quoted by Al Jazeera made the same point: the bomb is designed to produce a powerful blast across a surface area, not to reach deeply buried sites.

It also cannot be carried by a stealth bomber or a fighter. It needs a cargo aircraft flying over the target, which limits its use to airspace the US controls.

Mother vs. Father

In 2007 Russia announced its own giant bomb, the ATBIP, which it promptly dubbed the “Father of All Bombs”. Russia claimed a yield equivalent to 44 tons of TNT, four times the MOAB’s, from a lighter weapon of about 7.1 tonnes. Those figures have never been independently verified and are disputed. And the MOAB is not the heaviest bomb ever dropped: Britain’s 22,000-lb Grand Slam of 1945 weighed slightly more, although about half of that was its steel case. We tell the story of Barnes Wallis’s earthquake bombs in Tallboy and Grand Slam.

Explained in Under Five Minutes

A short explainer on the MOAB from Voice of America.

Common Myths

“It is a thermobaric bomb.” It is often called one, but strictly it is not a fuel-air weapon: its H-6 fill is a solid aluminised explosive, carried inside the case, not a fuel cloud dispersed and then ignited. “It is a bunker buster.” No, that is the GBU-57. “It is the most powerful non-nuclear weapon ever.” It was the most powerful in the US arsenal when it was developed; Russia claims its FOAB is more powerful, and the Grand Slam was heavier.

Sources: US Department of Defense, “What to Know About the GBU-43/B” (DoD Live, 14 April 2017); US Air Force and Air Force Armament Museum, Eglin AFB; Los Angeles Times (12 March 2003, and Al Weimorts obituary, 27 December 2005); Defense News; The New York Times, The Guardian and CBS News (13 April 2017); Stars and Stripes, on the Afghan death toll; Deutsche Welle and Wired (2007), on the Russian FOAB claims; Al Jazeera, “What is the ‘Mother of All Bombs’ US could use in Iran?” (15 October 2026), citing CNN; BBC News; PBS NewsHour; Voice of America.