How US Entry Into Iran-Israel Conflict Could Cripple Tehran’s Underground Nuclear Facilities

Last Updated:June 19, 2025, 10:45 IST

Fordow lies too deep for Israel to strike, but a US air campaign using GBU-57s, JASSMs, and decoy tactics could damage Iran’s nuclear programme at its core

US President Donald Trump and Iran's Supreme Leader Khamenei | AP Image

As the Israel-Iran conflict intensifies, the possibility of direct US military involvement has become a focal point of global concern. Beyond the broader geopolitical consequences, one specific outcome could be particularly consequential: a US-led airstrike campaign that targets and potentially cripples Iran’s underground nuclear facilities, particularly the heavily fortified Fordow Fuel Enrichment Plant.

While Israel has repeatedly targeted Iranian nuclear infrastructure over the years, it lacks the deep-penetration capabilities required to neutralise sites buried deep within mountains. The United States, however, possesses one unique asset that could change the game: the GBU-57 Massive Ordnance Penetrator, or MOP. In the event of American intervention, this weapon could pose the first real threat to Iran’s most secure nuclear sites.

What Makes Iran’s Nuclear Sites So Hard To Hit?

Iran’s nuclear programme is deliberately designed with survivability in mind. After facing years of sabotage, cyberattacks (like the Stuxnet virus), and airstrikes on above-ground facilities, Tehran moved critical operations underground.

The most prominent example is the Fordow Fuel Enrichment Plant, located near the holy city of Qom. This facility is buried beneath approximately 80 metres of rock and reinforced concrete, effectively shielding it from conventional airstrikes.

The Natanz facility, another major enrichment site, also contains underground halls but is less deeply buried than Fordow. While Israel has targeted surface and shallow subsurface sections of Natanz in past operations, Fordow has remained off-limits, not because of political restraint but because of physics.

Why Israel Can’t Strike Fordow Alone

Despite possessing state-of-the-art aircraft like the F-35I Adir stealth fighter, Israel’s air force lacks the ability to destroy Fordow’s buried centrifuge halls. The best penetrator munitions in Israel’s arsenal—such as the GBU-28 and BLU-109 bombs—can only reach depths of 20–30 metres, far short of the threshold needed to destroy Fordow’s reinforced mountain shield.

In fact, Israeli officials have previously asked Washington for access to the GBU-57, acknowledging that only the United States has the hardware needed for such a mission.

Without external support, Israel’s efforts are limited to disrupting Iran’s above-ground nuclear infrastructure or relying on cyberwarfare and covert sabotage. These tactics can slow Iran down, but cannot eliminate Fordow.

The Game-Changer: America’s Massive Ordnance Penetrator

The GBU-57A/B Massive Ordnance Penetrator (MOP) is the most powerful non-nuclear conventional bomb in the US arsenal. Specifically developed for destroying deeply buried targets, it weighs nearly 30,000 pounds (13.6 metric tonnes) and is capable of penetrating up to 60 metres of reinforced concrete before detonation.

It is GPS-guided, fitted with a smart fuse for delayed detonation, and built with a hardened steel casing that allows it to maintain structural integrity during penetration.

However, only one aircraft can deliver it: the US Air Force’s B-2 Spirit stealth bomber. This long-range bomber is capable of penetrating advanced air defence networks and reaching targets with minimal detection.

But while the MOP is the most powerful option, it is not the only one available to the United States.

Expanding The Arsenal: Beyond The MOP

Alongside the MOP, the US military can deploy a range of advanced precision-guided weapons that, together, increase the likelihood of significantly damaging Iran’s nuclear infrastructure. These munitions can be used to weaken surface defences, destroy support facilities, or soften specific targets before the MOP is deployed.

Among these are JDAMs (Joint Direct Attack Munitions) and JSOWs (Joint Standoff Weapons)—each weighing around 2,000 pounds—that can be dropped in a sequence to gradually breach reinforced structures. Military planners have described a “chisel-through" technique: one bomb creates an initial cavity, followed by another dropped into the same point to penetrate further. This layered bombing strategy can complement the MOP by preparing the ground and increasing its effectiveness.

The US also possesses JASSMs (Joint Air-to-Surface Standoff Missiles), which allow long-range, stealth attacks on surface-level or lightly hardened targets such as tunnel entrances, centrifuge control buildings, or air defence nodes, reducing risk to piloted aircraft.

Even smaller munitions like BLU-109 and BLU-116 bunker-busters, though incapable of reaching Fordow’s depth, are still valuable. They can destroy key surface infrastructure that supports underground operations—such as power stations, air vents, access tunnels, and communication lines—disrupting Iran’s ability to operate or protect the site even if the core remains intact.

Has The GBU-57 Ever Been Used In Combat?

No. As of mid-2025, the GBU-57 has never been deployed in a live combat situation. While multiple rounds of testing have validated its performance in controlled environments, there remains uncertainty about how effective it would be against a real-world target like Fordow, which may have added fortifications or decoy infrastructure.

According to defence analysts cited in The Washington Post and Financial Times, the bomb’s performance is reliable on paper, but actual combat effectiveness remains unproven.

What Would A US Strike On Fordow Involve?

A successful strike on Fordow would require:

One or more B-2 bombers, flying undetected into Iranian airspaceMid-air refuelling, as B-2s must fly from long distances (e.g., bases in Missouri or Diego Garcia)Precision GPS targeting to hit the exact underground coordinates of the centrifuge hallsAir-defence suppression, likely using drones or decoys to divert attentionPotential use of multiple MOPs, depending on Iranian structural upgrades or target redundancy

The US Air Force operates only about 20 B-2 bombers, making each such mission extremely high-value and logistically complex.

What Could Be Achieved

A direct strike on the Fordow facility using the Massive Ordnance Penetrator (MOP) could inflict severe damage on Iran’s underground nuclear infrastructure. If successful, such a strike could collapse centrifuge halls and crater access tunnels, rendering the site inoperable for years. It may also destroy stockpiles of enriched uranium, if they are stored at the targeted location, resulting in a substantial loss of Iran’s nuclear material.

Beyond the physical impact, the psychological effect would be significant. A successful US strike would shatter Tehran’s long-standing belief that its underground nuclear sites are immune to conventional attacks, thereby eroding the deterrence value Iran derives from their perceived invulnerability. Strategically, it could deal a major setback to Iran’s ability to reach “breakout" capacity—that is, the point at which it could rapidly develop weapons-grade uranium.

However, defence analysts caution that a single MOP may not be sufficient to eliminate the Fordow site entirely. Matthew Savill, head of military sciences at the Royal United Services Institute, told the Financial Times that “destroying such a structure would require successive hits with bunker‑buster bombs" because a single strike is unlikely to penetrate all the reinforced layers.

What Are The Strategic Risks

Any direct US involvement in striking Iran’s nuclear infrastructure, especially a site as symbolically and strategically significant as Fordow, would almost certainly escalate the ongoing conflict. One of the most immediate risks is retaliation against American forces stationed across the region, including military personnel and assets in Iraq, Syria, Bahrain, and throughout the Persian Gulf.

Iran could also launch missile or drone strikes on critical Gulf oil infrastructure, which would severely disrupt global energy markets. Another serious consequence could be the temporary closure of the Strait of Hormuz, a vital maritime chokepoint through which around 20 per cent of the world’s oil supply passes.

Additionally, Iran’s cyber capabilities pose a growing threat, with state-backed actors potentially launching retaliatory cyberattacks against US infrastructure and private-sector networks.

Beyond the military and economic repercussions, a strike on a nuclear facility carries far-reaching diplomatic consequences. It would all but eliminate the prospect of reviving negotiations over the Iran nuclear deal and could push Tehran to withdraw from the Nuclear Non-Proliferation Treaty (NPT), further destabilising the global non-proliferation framework.

Why Now? What’s Changed?

As per government sources, the US has begun preparing emergency evacuation plans for its citizens in Israel, widely interpreted as a precautionary step ahead of possible military escalation. In parallel, US forces have repositioned key assets closer to the region, including aerial refuelling tankers, F-22 Raptors, and B-2 Spirit stealth bombers, signalling heightened operational readiness.

In a public statement on June 17, President Donald Trump declared, “We want Iran to make an unconditional surrender," a remark that further underscored Washington’s hardening stance on Tehran’s nuclear programme. According to senior military officials quoted in The Washington Post, Iran’s Fordow enrichment facility is viewed as the most likely target if a strike is authorised.

Adding to the signals of advanced military preparedness, the E-4B Nightwatch—often referred to as America’s “doomsday plane"—was spotted landing at Joint Base Andrews near Washington, D.C. This aircraft is specially built to serve as a flying command centre during a major war or nuclear conflict. Its deployment is rare and is being seen by defence experts as a signal that the US is getting ready for all possible scenarios.

Will The US Strike?

President Trump’s position remains firm yet strategically ambiguous. On Wednesday, he stated on US military action: “I’m not looking for a fight with Iran, but we’re ready to act if we have to… I may do it, I may not do it. Nobody knows what I’m going to do. Nothing is finished until it is finished. The next week is going to be very big—maybe less than a week."

As per WSJ, Trump told aides he had approved military strike plans, including options against highly fortified targets such as Fordow, but stopped short of issuing a final order, choosing to await Iran’s response to his maximum-pressure tactics.

In sum, while no attack has yet been launched, the groundwork — including intelligence, weaponry, and personnel positioning — is firmly in place, and final authority rests squarely with Trump.

Final Word

If the United States chooses to enter the Iran-Israel conflict militarily, it will mark a turning point, not just in this regional war, but in the global nuclear balance. The Fordow facility, long considered unreachable, could be the centrepiece of that shift.

Location : First Published:

News explainers How US Entry Into Iran-Israel Conflict Could Cripple Tehran’s Underground Nuclear Facilities