Israel Seeks US GBU57 Bomb to Destroy Underground Iranian Nuclear Facilities.

According to information published by AP News on June 17, 2025, Israel has formally requested U.S. assistance to provide the GBU‑57 Massive Ordnance Penetrator (MOP), a 13,600 kg (30,000 lb) precision-guided bomb specifically engineered to neutralize deeply fortified underground military facilities. The request targets Iran’s Fordow nuclear site, located near Qom and constructed approximately 80 m below ground level within a solid mountain core, rendering it impervious to conventional Israeli ordnance. The MOP remains among the most closely guarded non‑nuclear munitions in the U.S. inventory, and Washington has yet to commit to its deployment or transfer. Its strategic value in this context lies not only in its sheer size but also in its ability to circumvent hardened geological protection layers that shield critical infrastructure.
Follow Army Recognition on Google News at this link

A U.S. B-2 Spirit stealth bomber in flight, the only aircraft capable of deploying the GBU-57 bunker buster (Picture source: US DoD)

From a technical perspective, the GBU‑57A/B MOP represents the apex of deep‑penetration conventional weapon design. The weapon body measures approximately 6.2 m in length and 0.8 m in diameter, with a total loaded weight of around 13,600 kg. It carries a massive 2,080 kg (4,590 lb) main charge of AFX‑757 high explosive, bolstered by a 341 kg (752 lb) PBXN‑114 booster, resulting in a total explosive mass exceeding 2,421 kg (5,342 lb) capable of generating an extreme penetrating force. Its thick steel casing allows it to breach up to 60 m of reinforced concrete or 40 m of hard rock. Internally, it is guided by an advanced GPS‑aided inertial navigation system (INS) providing accuracy within a few meters. The front‑end Large Penetrator Smart Fuze (LPSF) includes impact and void sensors enabling timed detonation within subterranean cavities like centrifuge halls, while a 155 mm crush set ensures penetration before fuze arming. Trapezoidal wings and lattice tail fins stabilize its high‑velocity, free‑fall trajectory, compensating for aerodynamic stresses upon release and maintaining flight control even in adverse wind conditions. The bomb can be released from high altitude and high speed to maximize penetration momentum, though such profiles necessitate precise launch planning. Currently, only the stealthy B‑2 Spirit is certified to carry two MOPs per mission load, offering low-observable delivery into contested airspace; integration with the forthcoming B‑21 Raider is expected once the bomber becomes operational.

The GBU‑57’s operational significance stems from its unparalleled ability to penetrate and destroy buried and hardened infrastructure that is immune to conventional and even earlier-generation bunker busters. In an environment where facilities like Fordow are encased in natural bedrock and enhanced with thick, reinforced concrete, lesser ordnance, such as the GBU‑28, BLU‑109, or even thermobaric options, fail to achieve target defeat. The MOP bridges this capability gap: by combining deep-penetration steel casing, a massive high‑explosive payload, precision guidance, and smart fuzing, it can collapse tunnels, rupture key chambers, and disrupt subterranean systems in a single strike. Its deployment would mark a strategic choice to neutralize Iran’s nuclear breakout infrastructure without resorting to nuclear weapons. Moreover, the bomb’s deployment would send a powerful message regarding U.S. resolve and technological advantage, reinforcing deterrence while offering precision engagement in deeply buried targets.

In the Israel–Iran conflict, deployment of the GBU‑57 would likely follow a highly coordinated US‑Israeli plan. Intelligence from Israeli satellites, drones, and signals intercept would be fused with U.S. mission planning systems to generate precise target coordinates. As Israel does not possess either the bomb or the B‑2/B‑21 platform, the strike would depend entirely on U.S. execution: stealthy B‑2 aircraft would launch from bases such as Whiteman AFB in the U.S. or forward positions if politically approved, penetrating Iranian airspace masked by low-observable signature and electronic warfare support. Upon reaching designated release points, the bomb would be dropped from altitudes above 50,000 feet and speeds exceeding 600 knots to impart the requisite kinetic energy for deep penetration. The integrated guidance and fuze systems would then ensure the bomb travels through rock layers, detecting when to detonate within voids to maximize damage to centrifuge cascades or command centers. The result could be the destruction of Iran's uranium enrichment infrastructure at Fordow in a single sortie. However, such an action would trigger sweeping consequences: militarily, Iran could launch asymmetrical retaliation via missile and drone strikes; regionally, proxy forces might escalate attacks on allied assets; diplomatically, it would complicate negotiations surrounding Iran’s nuclear deal and draw rebukes from global powers. Yet from a tactical standpoint, the GBU‑57 remains the only viable conventional ordnance capable of neutralizing a site buried to the depth and complexity of Fordow.

The United States has not engaged with Israel's request for the GBU-57 due to a combination of strategic, operational, and diplomatic considerations. The bomb remains a highly restricted asset, tightly controlled due to its destructive capability and classified deployment protocols. Granting access or authorizing its use could signal direct U.S. involvement in a unilateral Israeli strike on Iran, potentially igniting a broader regional conflict. Furthermore, Washington is cautious about undermining ongoing diplomatic efforts to manage Iran’s nuclear program through non-military channels. The operational secrecy surrounding the B-2’s mission profiles and the GBU-57’s capabilities also makes such cooperation exceptionally sensitive.