Bunker busting bombs B-61s are nuclear-tipped but still no guarantee against Iran's underground facilities - this changes everything

Most people don’t realise that most bunker busting bombs in the United States’ arsenal are ‘tactical’ nuclear weapons. The Western public is being re-directed to ooh and aah at the might of conventional earth penetrating weapons such as the GBU-57.

The primary objective of the US, if it enters Israel’s war against Iran, will be to destroy Iran’s Fordow uranium enrichment facilities buried in a mountain.

But even nuclear and conventional weapons combined aren’t guaranteed to do the job.

Context: Why nuclear components are used in bunker busting bombs

During the Cold War the US and the Soviet Union built underground facilities strong enough to protect from fallout in the event of a nuclear war.

Since the end of the Cold War in 1992, hardened underground cities and tunnels have become de rigueur for many countries. Hundreds of feet below the earth’s surface, they serve a variety of ‘national security’ purposes: a) concealment of weapons of mass destruction, b) covert transportation of weapons and personnel, c) fuel and food storage and d) command, control and communications. Up to 10,000 such facilities have been estimated in countries including the US, Russia, North Korea, China, Cuba, Israel and Iran.

Underground sites are hard to eliminate with conventional weapons alone, according to a National Security Archive Electronic Briefing Book report, ‘Many of the sites are greater than 20 meters below the surface, making some too deep to attack with conventional munitions.’

The emphasis has been on building tactical nuclear bombs with earth penetrating abilities below 20 meters. Such weapons are not covered under any arms treaties. The B61 nuclear bomb is the primary thermonuclear gravity bomb in the United States’ Enduring Stockpile.

Earth-penetrating weapon (EPW)

The EPW combines non nuclear components to penetrate soil, rock and concrete, with a nuclear component that when exploded, creates a strong seismic shockwave.

The nuclear-capable B61-11 is one such bomb. IDST, a San Jose based think tank notes that if exploded, ‘…significant amounts of rock and soil would be rendered radioactive and lofted as dust or vapor into the atmosphere, generating significant fallout.’

Iran’s Fordow nuclear enrichment plant is reportedly up to 80-90 metres (260-300 feet) under a mountain, and built to survive air strikes and bunker buster attacks.

US Department of Defense officials believe that incorporating bunker busting nukes is vital to destroying Fordow, reports the Guardian (UK.) ‘Defense officials who received the briefing were told that using conventional bombs, even as part of a wider strike package of several GBU-57s, would not penetrate deep enough underground and that it would only do enough damage to collapse tunnels and bury it under rubble…The defense officials were also told that to completely destroy Fordow, which Israeli intelligence estimates to go down as far as 300ft, it would likely require the US to first soften the ground with conventional bombs and then ultimately drop a tactical nuclear weapon from a B2 bomber.’

But there is no guarantee that even a nuclear explosive device would be effective, not least because of the difficulty of tracking underground sites and tunnels in Iran or anywhere else around the world.

In February 2025, two B-61-12 joint test assembly units are shipped at Sandia National Laboratories in New Mexico, US. It is the latest in the series of B-61 nuclear gravity bombs, and said to have the most accurate targeting. Source: https://newsreleases.sandia.gov/b61-12-sustainment/

Western media do not report on the nuclear components of the EPWs. Instead they focus on the conventional bunker busting GBU-57, illustrated here in this graphic published by CNN. It’s not clear whether its warhead contains so called ‘depleted uranium.’ Picture source.

‘Depleted’ Uranium Radioactive penetrators in bunker buster bombs

Another use of radioactive components is found in the penetrating warhead of bunker busting bombs.

These penetrators are made with uranium, because this metal is extremely strong and heavier than either steel or lead.

U-236/U-238 penetrators have been used by the US in Iraq, Afghanistan, Ukraine and the Balkans. The material called ‘depleted uranium’ (DU) aerosolises on impact, and has been linked to high cancer rates in US troops as well as in target populations.

In US and UK military parlance, it is characterised as ‘depleted uranium,’ which gives the impression that the danger DU weaponry and casings pose to human and environmental health is minimal. It’s a highly debated claim. Tests show that DU penetrates vital organs. The US and its allies have managed to bat away further investigation of DU health impacts, as called for by the United Nations General Assembly.

After Gulf War 1 (1991) I and others initiated a campaign against the use of the DU. Read here and here for updates. A documentary I co-produced describes the link between uranium illnesses suffered by Navajo miners and Gulf War 1 casualties, both troops and civilians. From Radioactive Mines to Radioactive Weapons is here.

Conclusion

A deal seemed close at hand with Iran last May. ‘Iran is ready to sign a nuclear deal with certain conditions with President Donald Trump in exchange for lifting economic sanctions, a top adviser to Iran’s supreme leader told NBC News on Wednesday.’ The deal didn’t work. Clearly Israel felt it still had a chance to attack and destroy Iran’s nuclear capabilities.

But it’s impossible to fully eliminate underground weapons of mass destruction sites, even with nuclear weapons.

The Zionist state’s hegemonic ambitions to be the only nuclear armed state in the region, is endangering the entire world. It is willing to risk a nuclear confrontation in order to defend itself against a potential nuclear strike. The logic is incomprehensible.

The long-term solution must be one forged in diplomacy. A Middle East Nuclear Weapons Free Zone must be established, following the example of weapons free zones in Central Asia, Africa and Latin America. The first annual conference for a MENWFZ was held in 2019 with 22 members of the Arab League and Iran, as well as four nuclear-armed states China, France, Russia, and the United Kingdom. Only Israel and the US did not participate.

Update. On June 21, 2025, the US attacked Fordo in violation of Article 51 of the UN Charter. Doubts about the efficacy of the strike were raised: ‘Anybody who says that they have any idea whatsoever about whether these raids did anything other than create a big boom and a lot of dust has no idea what they’re talking about,’ Rep. Jim Himes, the top Democrat on the House Intelligence Committee, told CNN’s Kasie Hunt on “State of the Union” on Sunday June 22.

Other references

Why America's B-61-12 Nuclear Bomb Is Tempting to Use During a War - The National Interest

https://thebulletin.org/2024/02/why-the-biden-administrations-new-nuclear-gravity-bomb-is-tragic/

https://science.howstuffworks.com/bunker-buster.htm

https://digital-commons.usnwc.edu/cgi/viewcontent.cgi?article=1808&context=ils

https://kffhealthnews.org/morning-breakout/investigation-reveals-startling-spike-in-cancer-for-soldiers-who-served-in-iraq-afghanistan/