The 2026 Iran–U.S.–Israel War will be studied for years to come across many dimensions of cyber, air, and naval warfare, as well as in relation to capabilities such as air power, air-defense missiles, ISR (Intelligence, Surveillance, and Reconnaissance), electronic warfare, ballistic, hypersonic, and cruise missiles, armed unmanned aerial and maritime vehicles, mines, and precision-guided munitions. Yet perhaps one of the war’s most important lessons emerged not in the skies or on the surface, but hundreds of meters below ground. Iran’s underground missile facilities, command-and-control centers, storage sites, and production facilities, constructed over many years deep inside mountainous terrain, managed to survive despite weeks of intensive attacks by U.S. and Israeli air power.

These sites sustained serious damage under intensive air strikes. Missile bases, production facilities, tunnel entrances, boat shelters, and launcher infrastructure were significantly damaged. Nevertheless, it proved impossible to destroy the entirety of Iran’s missile and armed unmanned aerial vehicle capabilities that had been relocated underground. Some tunnel entrances were reopened, certain facilities were brought back into operation, and despite intensive bombardment, Iran was able to continue missile launches, fast-attack craft operations, and armed UAV attacks during the later stages of the war. Post-war assessments indicate that Iran was able to preserve a significant portion of its missile stockpile and mobile launchers.

Iran’s extensive underground infrastructure programme, developed over the past forty-five years since the 1980s, was tested for the first time in a real war on this scale. Iran’s success in this regard should not be measured solely by the number of targets it struck. What matters is its ability to survive against two of the world’s most powerful air forces. In other words, Iran demonstrated an ability to preserve its capacity for resistance even after the enemy’s initial and potentially devastating strikes. It achieved this largely by going underground. This success in maintaining resilience is likely to serve as an example for many states of the Global South that may, in the future, face threats, coercion, or attack by hegemonic powers.

The Earth’s Surface and Airspace Are Becoming Increasingly Transparent

A profound transformation is taking place in the battlespace of the twenty-first century. Lessons drawn particularly from the Russia–Ukraine War have demonstrated that, owing to satellite systems, cyber capabilities, synthetic aperture radar (SAR), electro-optical sensors, signals intelligence, unmanned aerial and maritime vehicles, electronic intelligence, AI-assisted imagery analysis, and long-range precision-guided weapons, it has become increasingly difficult to conceal large military forces on the surface or in the air. Compared with the past, detecting a tank battalion, an air-defense battery, a missile launcher, a command center, a logistics concentration, or virtually any object approaching through the air has become considerably easier. Moreover, the challenge is no longer merely one of detecting a target; in modern warfare, the time between detection and engagement has also been dramatically compressed. A satellite, radar, or unmanned aerial or maritime vehicle detects a target, its coordinates are transmitted through the command network, and shortly thereafter a precision-guided munition or armed UAV is directed against it. With the integration of artificial intelligence, the decision cycle from detection to engagement is becoming increasingly automated.

The ability of UAVs to detect and strike vehicles even tens of kilometers behind the front line has significantly increased both the risks and costs of operating on the surface. In short, as technology makes the Earth’s surface increasingly visible, warfare is shifting towards domains that remain concealed from observation. One of these domains is underground; the other is beneath the surface of the sea.

Underground Warfare Is Not New

Humanity has made use of the underground environment, particularly tunnels, for thousands of years. Since antiquity, tunnels have been excavated beneath fortifications during siege warfare. One of the earliest and most institutionalized examples of underground warfare in Ottoman military history can be found in the Lağımcılar, or military miners. Their task during sieges was to excavate galleries beneath enemy fortifications, weaken their foundations, and use gunpowder to breach defensive walls. During the Siege of Constantinople in 1453, Ottoman miners dug tunnels to penetrate beneath the city walls. During the conquest of Crete, particularly the Siege of Candia (1648–1669), an almost entirely separate front emerged beneath the fortifications, where Ottoman and Venetian forces conducted extensive mining and counter-mining operations.

During the First World War, kilometers of underground galleries were constructed to place explosives beneath enemy trenches. In the Second World War, Japan extensively used caves and tunnels on Pacific islands to protect its forces against overwhelming American air and naval firepower. In Vietnam, underground warfare reached another level. The Cu Chi tunnel system was not merely a network of passages in which soldiers could hide. Command centers, hospitals, ammunition depots, kitchens, living quarters, and logistical connections were all moved underground. The U.S. military enjoyed overwhelming control of the air and possessed a degree of firepower that the Viet Cong could not match. Yet this superiority diminished only a few meters beneath the surface. The underground environment effectively functioned as a force multiplier that reduced the advantages provided by technological superiority.

.

Inside the Cu Chi Tunnels in Viet Nam. Infamous and effective during the war, the tunnels are now a popular tourist attraction. Photo taken by Wikimedia Commons user Kevyn Jacobs, released into the public domain.

.

One country that elevated this approach from the tactical to the strategic level was North Korea. The destruction caused by American air superiority during the Korean War left a profound impression on Pyongyang. As a result, North Korea began moving not only its troops but also a significant portion of its military infrastructure underground. Command centers, artillery positions, ammunition depots, air bases, and later missile facilities were constructed inside mountains. At this point, the issue was no longer a matter of tunnels extending for a few kilometers, but rather an entire military ecosystem relocated underground. This experience is also relevant to Iran. There are significant assessments suggesting that North Korean experience influenced the development of Iran’s missile forces. Analyses published after the 2026 war also drew attention to lessons that Iran’s former missile forces commander, Amir Ali Hajizadeh, had reportedly derived from North Korea’s underground systems.

One of the most striking modern examples of underground warfare has also been seen in Gaza. Initially, Gaza’s tunnels were relatively simple structures used primarily for smuggling, infiltration, and concealment, but over time they evolved into a far more sophisticated military infrastructure. Command centers, weapons depots, communications networks, personnel movement corridors, and facilities designed for prolonged habitation were transferred underground. The strategic consequence was considerable. Although Israel exercised complete control over the airspace above Gaza, it was unable to establish an equivalent degree of control beneath its surface. Iran and Gaza represent very different cases, but they share one fundamental characteristic: the strategic-scale use of the underground domain as a means of protection against increasingly sophisticated sensor and intelligence systems.

Iran: From Tunnels to Missile Cities

Iran applied the logic of underground warfare seen in Gaza across a much larger geographical area and at the scale of a state. Behind this approach lay Iran’s fundamental military vulnerability. Iran could not compete symmetrically with the United States or Israel in terms of modern air power. It therefore based a significant part of its deterrence posture and warfighting doctrine on ballistic and cruise missiles, as well as armed unmanned aerial and maritime vehicles, to generate asymmetric effects. Possessing these capabilities, however, was not sufficient. These systems also had to survive the enemy’s initial strikes and retain the capacity for replenishment and reproduction. Iran’s solution was to move a significant proportion of its missile, armed UAV, and related capabilities deep inside mountainous terrain.

This led to the emergence of extensive underground complexes commonly referred to as “missile cities.” These evolved into large military facilities in which missiles could be stored and prepared for launch, mobile launchers could maneuver, and command-and-control activities could be conducted. The 2026 war became the first real test of this doctrine. For weeks, U.S. and Israeli air forces systematically targeted Iran’s missile infrastructure. The attacks inflicted serious damage, particularly on surface infrastructure, tunnel entrances, production facilities, and launch systems. Completely eliminating the underground system, however, presented an entirely different challenge.

One of the most striking examples of Iran’s underground warfare concept emerged in Yazd, in the central part of the country. The Imam Hussein Strategic Missile Command Center, located inside the mountains south of Yazd, had become one of the principal centers of Iran’s long-range ballistic missile force. During the war, U.S. and Israeli air forces repeatedly bombed the mountainous area around Yazd for approximately forty days. Yet these attacks failed to bring missile activity to a complete halt. Open-source data and reports from the region indicated that missile launches continued from the area even while the bombardment was ongoing. Satellite imagery taken after the war also showed that damaged tunnel entrances were being cleared, access roads reopened, and efforts to restore the facilities to operational status initiated rapidly.

The significance of the Yazd example lies precisely in this. Iran did not merely store its firepower underground; it transferred an entire warfighting infrastructure into the mountain. Consequently, even if an attacker destroyed entrances, roads, and facilities outside the mountain, eliminating the entire system inside became considerably more difficult. The effectiveness of underground facilities should therefore be measured not by whether they can avoid being struck, but by their ability to continue fighting after being struck. The fact that missile activity around Yazd could not be completely suppressed despite approximately forty days of bombardment is perhaps one of the clearest examples of how mountains and the underground domain have once again become strategic defensive spaces in twenty-first-century warfare.

According to U.S. intelligence assessments reported after the war, Iran was estimated to have preserved approximately 70 per cent of its pre-war mobile launchers and missile stockpile. It was also reported that some tunnel entrances were reopened after being struck and that missile launches subsequently resumed from the same areas. The fundamental objective of Iran’s underground strategy was to prevent the complete destruction of its missile force. Viewed from this perspective, the system fulfilled its intended function to a significant extent.

In this context, the principal lesson of the Iranian experience is that modern underground defense is not simply a matter of going deeper. The approach observed, for example, at Fordow and Natanz is based on using the mountain mass itself as natural armor, placing facilities beneath tens of meters of rock, constructing long and indirect access tunnels, separating critical sections from one another, and providing multiple entrances and ventilation systems. Protection thus becomes a multilayered architecture combining depth, compartmentalization, redundancy, and natural geology. Concrete is also important, but it is only one element of this system rather than the sole determining factor. The precise grade of concrete used in Iranian facilities has not been verified through open sources. Nevertheless, in modern protective structures, high-strength concrete in the range of 60–120 MPa (megapascals) can provide substantial protection, while more advanced applications may employ UHPC (Ultra-High-Performance Concrete) or UHPFRC (Ultra-High-Performance Fiber-Reinforced Concrete) with compressive strengths exceeding 150 MPa. The principal lesson to be drawn from Iran, therefore, is not simply to construct an exceptionally strong concrete wall, but to combine high-strength concrete with tens of meters of natural rock, substantial depth, compartmentalized galleries, and a redundant tunnel network.

.

The entrance to the Natanz nuclear facility on the old Kashan-Natanz road (CC BY-SA 4.0)

.

Air Superiority Is Not Everything

The Iran–U.S.–Israel War has reopened the debate over a longstanding military concept: does air superiority necessarily mean dominance over the entire battlespace? Through the destructive firepower and psychological shock, it generates on the surface, air superiority often provides a major advantage. Yet the equation changes when the battlespace extends underground. An air force can strike an adversary’s runways, radars, energy infrastructure, air-defense systems, and surface-based missile launchers. However, when a significant portion of the adversary’s warfighting capability is located beneath tens or even hundreds of meters of rock, the targeting challenge becomes fundamentally different. Tunnel entrances must first be identified, the geometry of the underground complex must then be understood, and finally the appropriate munitions must be employed. Moreover, collapsing an entrance does not necessarily mean that the facility itself has been destroyed.

In Iran, some facilities appear to have sustained damage that temporarily suppressed their operations rather than permanently destroying them. Given sufficient time and repair capabilities, Iran was able to reopen some of these entrances. There is a major strategic difference between suppressing a missile base for several days and eliminating it to the extent that it cannot be used for the remainder of the war. This distinction stems largely from the inherent difficulty of destroying well-protected caves and underground shelters with conventional weapons.

Comparable manifestations of the Iranian experience can be observed today in China, North Korea, Russia, Ukraine, and other countries. As satellites, UAVs, persistent surveillance, artificial intelligence, and precision-strike systems make surface activities increasingly observable and vulnerable, the strategic value of operating underground continues to grow. Future military infrastructure will therefore include not only long-range missiles and advanced dome-type air-defense systems described by various labels—such as Iron, Steel, or Golden—but also underground and protected command centers, ammunition depots, armed UAV hangars, missile launchers, production facilities, and logistical infrastructure. In other words, the battlespace is becoming increasingly vertical as well as horizontal.

Beneath the Sea

The same fundamental dynamic that is driving military forces underground on land is also at work at sea: what is visible is becoming increasingly vulnerable to targeting. Satellite reconnaissance, UAVs, radar, electro-optical systems, and AI-assisted targeting are making the surface progressively more transparent. If a warship remains on the surface, it is exposed to this reconnaissance and targeting network. The submarine’s greatest advantage, even before its firepower, is its ability to remain unseen. Thus, what mountains, caves, and underground shelters provide on land is provided by depth at sea. Both reduce visibility, limit sensor effectiveness, and complicate the adversary’s targeting chain.

The history of naval warfare is replete with examples of this dynamic. The reason the Dardanelles Campaign—which contributed to prolonging the First World War by two years—was launched was the failure of the combined British and French invasion armada to force the Straits on 18 March 1915, owing in large part to the 26 mines laid by the Nusret. Mines concealed beneath the surface had altered the course of the war. During the Second World War, U.S. submarines played a critical role in the collapse of Japan’s economic and military logistics by destroying a substantial proportion of the Japanese merchant fleet and maritime transportation system in the Pacific. In the Atlantic, German U-boats sought to sever Britain’s maritime lifelines. This was why Churchill stated that the U-boat threat was the one thing that truly frightened him during the war. The submarine’s strategic power derived from its ability to threaten a military and economic system far larger than itself while remaining unseen.

Despite the passage of eighty years, this physical advantage has not disappeared. Notwithstanding extraordinary advances in artificial intelligence, big data, satellite systems, and unmanned platforms, the complex laws of acoustics continue to govern the underwater environment. Water temperature, salinity, pressure, water-column stratification, seabed topography, and ambient noise all complicate the detection problem. For this reason, the submarine’s most important weapon is not its torpedo or missile, but first and foremost its ability to avoid detection. This is also the principal reason why ballistic-missile submarines continue to constitute the most survivable component of nuclear deterrence.

In the second quarter of the twenty-first century, underwater warfare is no longer confined to manned submarines. Unmanned Underwater Vehicles (UUVs), long-range autonomous underwater vehicles, seabed sensors, and underwater communication systems are creating an entirely new ecosystem. Just as possession of submarines was a strategic capability limited to a relatively small number of states in the previous century, the ability to operate long-range, independently deployable autonomous underwater systems in conjunction with manned submarines is likely to create a similar strategic distinction in the coming era.

The next stage of underwater competition is seabed warfare. Intercontinental fiber-optic cables, energy pipelines, electricity interconnectors, sensors, and communications systems are located on or beneath the seabed. Consequently, the underwater domain of the future will not merely be an environment in which submarines seek to detect and destroy surface ships and other submarines. It will become a distinct strategic front encompassing critical infrastructure, unmanned systems, and operations conducted both against and in defense of them. As the battlespace expands outward into space, it is simultaneously extending downward towards the ocean floor. As surface operations become increasingly transparent, the next major technological competition will shift towards which side can see beneath the sea first.

It is therefore insufficient to interpret the future of naval warfare solely in terms of more ships or greater numbers of unmanned surface vehicles. The decisive competition will increasingly revolve around which side can remain unseen, detect the adversary first, and preserve the survivability of its command-and-control system under attack. The survivability demonstrated on land by Iran’s underground missile cities and the concealment provided at sea by submarines are, in essence, two different applications of the same strategic principle. As the surface becomes more transparent, warfare is shifting into the depths. Future superiority will belong to the side capable of hiding in the depths, seeing into the depths, and controlling the depths. Accordingly, discussions of future defense architecture must address not only the weapons and platforms themselves, but also how their survivability can be ensured. From this perspective, Iran’s experience in the 2026 war warrants careful examination.

Conclusion

The enduring dialectic of warfare is the competition between firepower and survivability. As artillery became more powerful, trenches grew deeper; as air power developed, fortifications moved underground; and as reconnaissance and surveillance capabilities expanded, methods of camouflage and deception evolved accordingly. Today, the convergence of satellites, radar, UAVs, electronic intelligence, artificial intelligence, and precision-guided weapons is making the Earth’s surface transparent to an unprecedented degree. The natural consequence is an escape from the surface. From the shallow tunnels of Cu Chi during the Vietnam War to the mountains of North Korea, and from Gaza’s underground networks to Iran’s missile cities carved deep into rock, these examples represent different stages of the same historical trajectory. The Iran war has demonstrated the strategic dimension of this transformation. Underground facilities do not provide absolute invulnerability, but locating them, striking them, assessing the resulting damage, and striking them again dramatically increase the time, munitions, and intelligence effort required from the attacker. The underground domain should therefore no longer be regarded merely as a shelter, but as a distinct battlespace capable of eroding technological superiority and enhancing the survivability of strategic firepower. Following these experiences, future assessments of military geography will inevitably attach greater importance to mountainous terrain containing caves, as well as other natural features capable of providing concealment and protection.

This issue also represents an important model of defense architecture that deserves serious consideration from Türkiye’s perspective. Türkiye’s geography offers significant natural advantages in this regard. The Taurus Mountains with their extensive and massive mountain formations, provide a natural environment that can in certain respects be compared with Iran’s Zagros mountain belt, while the high and rugged terrain of Eastern Anatolia offers similar potential. Cappadocia, meanwhile, demonstrates through historical examples such as Derinkuyu and Kaymaklı that the construction of large underground spaces has long been feasible in Anatolia. However, because of the mechanical characteristics of its volcanic formations, the Cappadocian model should not be placed in the same category as the protection afforded by hard-rock mountain masses.

The principal lesson for Türkiye, therefore, is not simply to convert existing caves into shelters, but rather to integrate mountains and geology into the architecture of national defense. The Taurus Mountain belt is particularly noteworthy in this respect. Nevertheless, the suitability of an underground facility cannot be assessed solely according to the height or thickness of the mountain above it. Rock mechanics, fault and fracture systems, seismic risk, groundwater conditions, and long-term structural stability must all be evaluated together.

The same transformation is now taking place beneath the seas. Submarines, Unmanned Underwater Vehicles (UUVs), fixed and mobile sonar networks, seabed sensors, cables, pipelines, and energy interconnectors are turning the underwater domain into a distinct battlespace. The struggle of the future will therefore involve not merely an escape into depth, but a competition for the control of depth. While one side seeks concealment underground or underwater to evade sensors, the other will attempt to make these domains transparent once again through seismic and acoustic sensors, sonar networks, unmanned systems, satellite-derived data, and artificial intelligence. One of the fundamental military questions of the twenty-first century may therefore become: “Having made the surface transparent, who will make the depths transparent?” For many states, the strategic objective will be not only to construct underground infrastructure capable of surviving an initial strike, but also to establish an integrated underwater situational awareness architecture capable of detecting, mapping, protecting, and, when necessary, exploiting the underwater domain.

In summary, as Türkiye enters an era of intensifying strategic competition in the twenty-first century, it should seek to employ both the underground and underwater domains as force multipliers.

*

Click the share button below to email/forward this article. Follow us on Instagram and X and subscribe to our Telegram Channel. Feel free to repost Global Research articles with proper attribution.

This article was originally published on Mavi Vatan.

Ret Admiral Cem Gürdeniz, Writer, Geopolitical Expert, Theorist and creator of the Turkish Bluehomeland (Mavi Vatan) doctrine. He served as the Chief of Strategy Department and then the head of Plans and Policy Division in Turkish Naval Forces Headquarters. As his combat duties, he has served as the commander of Amphibious Ships Group and Mine Fleet between 2007 and 2009. He retired in 2012. He established Hamit Naci Blue Homeland Foundation in 2021. He has published numerous books on geopolitics, maritime strategy, maritime history and maritime culture. He is also a honorary member of ATASAM. 

He is a Research Associate of the Centre for Research on Globalization (CRG).

Featured image is from the author

Global Research is a reader-funded media. We do not accept any funding from corporations or governments. Help us stay afloat. Click the image below to make a one-time or recurring donation.