Digging Deeper: How Underground Infrastructure Undermines US Strikes and Empowers Adversaries

Small Wars Journal | Samuel Esselman

The operations carried out under the names Operation Midnight Hammer and Epic Fury have demonstrated the limits of the United States' capacity to carry out accurate strikes on Iran's well-protected underground facilities. Despite 14 large ordnance-penetrating bombs being dropped on Natanz and Fordo, declassified intelligence assessments indicate that the Iranian military has regained access to 90 per cent of its underground missile storage sites.

The fact that such resilience exists is a result of decades of deliberate investment in deeply buried infrastructure, as can be seen in the case of the Yazd base, which is situated 500 metres below a natural granite formation. The key retaliatory facilities are safeguarded by hardened tunnels. When one examines these operations, countries like China and North Korea are accelerating their own underground programmes in order to offset American power projection. The People's Liberation Army has constructed more than 13 super-hardened airbases and large naval tunnels at Jianggezhuang and Yulin in order to secure its assets. Ultimately, this global trend towards underground defence is likely to make the United States' traditional method of relying on kinetic coercion and rapid power projection obsolete.

Comment

The United States Air Force's reliance on the GBU-57 Massive Ordnance Penetrator, which is dropped by B-2 Spirit bombers, is now nearing a fundamental limitation in dealing with adversaries that have facilities deeply buried beneath the ground. Cases like the Yazd base demonstrate that geological shielding can counter the kinetic energy delivered by conventional bunker-busters. This raises doubts about the fundamental principle of the United States Joint Chiefs of Staff's joint targeting cycle, namely that any important target can be destroyed by means of accurate coordinates. Consequently, since the GBU-57 cannot ensure the destruction of the buried nuclear facilities at Fordo, a change in doctrine is required, involving a shift from pre-emptive counter-force strikes to long-term containment.

The fact that this doctrinal failure has taken place is attributable to the structural geology of the Zagros Mountains, as the granite formations take in the shockwaves from GBU-57 penetrators before they can reach the underground chambers. This geographical characteristic causes the United States Central Command to change the focus of its targeting cycle from the direct destruction of the Yazd bunker to the interception of external nodes, such as ventilation shafts and tunnel portals. However, as the rapid reopening of Iranian tunnel exits during Operation Epic Fury demonstrated, these interdiction operations only result in temporary operational interruptions and not in permanent strategic denial.

Strategic Question for Discussion

What impact would it have on the United States Joint Chiefs of Staff's joint targeting cycle if the GBU-57 Massive Ordnance Penetrator was rendered ineffective by the facilities at the Yazd base which are protected by granite?

What the course of action indicates is that the joint targeting cycle would have to shift from the kinetic destruction of the facility to the systemic isolation of its external nodes. I think that this change would enhance the significance of cyber operations and electromagnetic warfare designed for disrupting the internal automated rail systems and the communications of the Yazd base. Ultimately, this approach replaces immediate physical destruction with prolonged operational disruption, on the understanding that the core assets will still be out of reach.

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