The US dropped bunker-buster explosives on Yemen’s underwater weapons depots in a high-stakes show of force, the latest indicator that the Gaza conflict is roiling the area.
The US’s first use of a bomb in the region was reported by a number of media outlets this month as the country’s B-2 Spirit cunning planes were used to attack underwater arms storage facilities run by Yemen’s Iran-backed Houthi rebels.
Five bunkers housing weapons used in attacks on ships in the Red Sea were reportedly bombed by the B-2s with GBU-57 Massive Ordnance Penetrator ( MOP)/B bunker-buster bombs.
US Defense Secretary Lloyd Austin characterized the attack as a presentation of the US’s ability to attack seriously buried and fortified sites, pointing out that US President Joe Biden had authorized it to destroy the Houthis ‘ ability.
In response to the Gaza issue, the Houthis have increased their weapon and drone attacks, including those against Jewish and US goods, by attacking over 80 arteries since October 2023.
In light of the ongoing hostility between Israel and the US, the hit also served as an implicit warning to Iran, a crucial Houthi supporter. Despite the advanced character of the activity, no immediate civilian deaths were reported.
While information about the GBU-57 MOP/B remain defined, Global Security mentions that the weapons is a strong, precision-guided weapon weighing roughly 13, 600 pounds and containing over 2, 400 kg of explosives that is designed to reach deeply buried targets.
Global Security says GPS-aided Inertial Navigation System ( INS ) guides the bomb, which can be deployed from B-52 and B-2 bombers and can breach 61 meters of 34.5 megapascal ( MPa ) reinforced concrete or 38 meters of moderately hard rock.
In a June 2020 Missile Threat report, Ian Williams and Shaan Shaikh notice how Houthi rebels have constructed advanced underwater features to conceal and protect their missile rockets, making them more difficult to identify and damage.
These underground locations are where ballistic missiles are stored and launched, according to Williams and Shaikh, and have been used to obliterate Red Sea shipping and strike Saudi Arabian targets.
They claim that Houthi media frequently features these secret missile sites to highlight their ability to evade aerial surveillance. In addition, they claim that the tactic, combined with the use of drones for reconnaissance, allows the Houthis to continue to have a resilient missile arsenal despite coalition airstrikes hitting their launch locations and missile arsenals.
Additionally, even technologically advanced forces like the US are challenged by the Houthi’s use of tunnel warfare.
In an August 2023 article in the peer-reviewed Studies in Conflict and Terrorism journal, Daphné Richemond-Barak and Stefan Voiculescu-Holvad mention that tunnel networks undermine modern precision warfare at the strategic level. They claim that destroying tunnel networks necessitates a lot of resources for detection and neutralization, which frequently results in significant collateral damage and limited long-term effects.
Despite those challenges, the US use of B-2s with MOP bombs in Yemen may hint at its concept of conventional deterrence.
Robert Haffa Jr. mentions that conventional deterrence focuses on preventing aggression through the use of advanced conventional military capabilities, with the crucial components of capability, credibility, and communication still being important. In a 2018 article for Strategic Studies Quarterly, Robert Haffa Jr. mentions that.
Haffa Jr. argues that conventional deterrence relies on strong, quick, and effective forces supported by advanced technologies like stealth, stealth, and cyber capabilities, and succeeds by making aggression expensive and futile.
The Houthis ‘ B-2 strikes using MOP bombs demonstrate the US’s ability to launch long-range precision strikes against fortified targets, refuting Haffa’s theory.
Although Iran’s secret nuclear facilities have been identified as potential targets for US or Israeli bunker-busting strikes, its underground missile and air bases could also be used as a staging ground for such attacks.
In February 2023, Asia Times reported on Iran’s unveiling of the Oghab-44 underground air base, marking a significant enhancement in its military capabilities, particularly for maritime precision strikes in the Persian Gulf.
Oghab-44, located northeast of Bandar Abbas, protects Iran’s aging pre-1979 aircraft, including F-4 Phantoms, from pre-emptive strikes. Equipped with critical facilities, it supports Iran’s asymmetric anti-access/area-denial ( A2/AD ) strategy, enabling surprise strikes and precision retaliation against US naval forces in the Persian Gulf.
Beyond the Middle East, the US’s use of B-2 bombers to drop MOP bombs also sends a clear message to North Korea, which may concern China because its submarine base in Hainan opens onto the South China Sea.
Joseph Bermudez Jr. and other authors make reference to North Korea’s continued improvement of its missile capabilities in a part-1/”>two-part Beyond Parallel report from 2024, which is crucial for concealing and safeguarding its ballistic missile systems.
The Hoejung-ri Missile Operating Base near the Chinese border is currently being built, including a new building right next to an underground missile facility, according to Bermudez Jr. and others. They point out that this base and other locations like Goal and Kumchon-ni are located within North Korea’s strategic missile belt.
In a separate November 2018 Beyond Parallel report, Bermudez Jr and other writers mention North Korea deploys its missiles at three belt locations: strategic, operational and tactical, based on their distance from the Demilitarized Zone ( DMZ).
More than 150 kilometers north of the DMZ lies North Korea’s strategic missile belt. It was first equipped with Nodong missiles, and it likely has more recent Hwasong missiles. The operational belt is , 90-150 kilometers north of the DMZ and , equipped with Nodong medium-range ballistic missiles or longer-range systems.
Finally, the , tactical belt, located 50-90 kilometers north of the DMZ, is equipped with Scud short-range ballistic missiles ( SRBM ) and covers critical facilities in northern South Korea.
As for China, CNN reported in August 2020 that satellite imagery revealed a Chinese Type 093 nuclear-powered attack submarine ( SSN) entering an underground base on Hainan Island’s Yulin Naval Base.
This unusual sighting, according to CNN, highlights China’s strategic use of underground facilities to conceal military assets, improve operational security, and make adversary surveillance more difficult.
However, even a conventional attack on North Korea’s missile forces and China’s undersea nuclear deterrent, despite its “no-first-use”  , nuclear policy, may still prompt a nuclear response from both potential US adversaries.