The Next Domain of Warfare Lies Underground

Palmer Luckey recently went viral arguing that the next domain of warfare will be subterranean. He is right, although probably not in the way many people understood it. Most people heard the comment and immediately thought about tunnels, bunkers, or trench systems. Luckey was talking about something much larger: a future where the surface battlefield becomes so exposed, so constantly monitored, and so lethal that militaries increasingly maneuver beneath the Earth itself. In his framing, the crust of the Earth becomes a warfighting domain in the same way undersea warfare emerged once submarines matured into viable military systems.

That idea sounds futuristic until you look at modern warfare. In Ukraine, soldiers increasingly survive by disappearing underground. The front line is now covered by fiber optic drones, thermal optics, loitering munitions, satellites, and precision artillery. Movement on the surface can trigger strikes within minutes. Russian and Ukrainian forces have responded by digging deeper trench systems, connecting trench lines through tunnel networks, burying command posts, and moving critical wartime functions beneath the surface whenever possible. Russian forces have built extensive underground pathways near portions of the front that function almost like protected highways for movement and logistics. In multiple sectors, Russian soldiers have attempted to crawl through abandoned gas pipelines to bypass drone-covered death zones and infiltrate Ukrainian positions from unexpected directions. Ukraine has responded in different ways, moving drone manufacturing, command nodes, medical facilities, and other critical functions underground to survive constant attack. Much of the war already resembles a shallow subterranean conflict interrupted by brief periods of exposed movement.

The same pattern appears elsewhere. Hamas built one of the most extensive underground military systems in modern history beneath Gaza. Iran buries missile systems, command centers, and nuclear infrastructure underground because it assumes anything visible above ground can eventually be targeted. Hezbollah spent years constructing hardened underground networks across southern Lebanon. China has invested heavily in thousands of miles of subterranean military infrastructure for decades. Nations already place what they value most underground because the modern battlefield increasingly punishes exposure.

What Luckey is talking about goes far beyond defensive tunneling or hardened bunkers. Militaries have buried command posts, missile systems, factories, and leadership facilities underground for decades because underground infrastructure improves survivability. Luckey is talking about maneuver underground. During the Cold War, both the United States and Soviet Union explored concepts driven by fears that nuclear weapons, long-range fires, and advancing surveillance capabilities would make the surface battlefield increasingly vulnerable. American efforts focused largely on survivability and underground infrastructure projects such as Project Iceworm in Greenland. Soviet planners reportedly went further, exploring experimental “Battle Mole” concepts, including a proposed nuclear-powered tunneling vehicle envisioned to move through solid rock beneath enemy defenses, strike infrastructure, sabotage facilities, or deliver explosives underground.

Military planners understood that advances in detection and firepower could eventually make the surface battlefield extraordinarily dangerous. Some believed the Earth’s crust itself would become contested terrain where forces moved logistics, weapons, equipment, and potentially combat power beneath the surface much like submarines maneuver beneath the sea. Luckey referenced that directly in a recent discussion, arguing that both superpowers believed “the crust of the Earth would turn into a battle space.”

The comparison to submarines is more than metaphor. Before submarines, naval warfare existed almost entirely on the surface. Fleets maneuvered visibly. Once submarines matured technologically, they fundamentally altered naval power because they could bypass surface defenses and move unseen beneath stronger fleets. A battleship could dominate the surface and still remain vulnerable to something it could neither see nor easily stop. Modern land warfare may be approaching a similar transition.

For centuries, armies focused on terrain they could physically observe. Rivers, mountains, fortifications, urban areas, trench systems, and defensive belts shaped military operations above ground. Even today, militaries invest enormous resources breaching minefields, crossing anti-tank ditches, suppressing defensive positions, and forcing passage through heavily defended terrain. The modern battlefield has only intensified those challenges because drones now observe many of those movements in real time. A trench line is already a crude subterranean maneuver system designed to reduce exposure to the surface battlefield.

History repeatedly demonstrates the military value of underground movement. One of the oldest examples comes from the biblical account of King David’s forces infiltrating Jerusalem through a water channel beneath the city. Siege mining became common throughout ancient and medieval warfare because tunneling allowed attackers to bypass walls and defenses directly. Underground warfare also played a major role in the positional fighting of World War I, where both sides dug massive tunnel systems beneath trench lines to plant explosives, protect forces, and survive industrial-scale artillery fire. For most of history, however, subterranean warfare largely favored defensive survival, attrition, or localized infiltration rather than rapid maneuver.

During the Vietnam War, the Viet Cong used extensive tunnel systems to survive American firepower and maneuver against technologically superior forces. Hamas applied many of the same principles in Gaza on a vastly larger scale. The operational advantage has remained remarkably consistent across centuries: underground movement reduces exposure to surveillance and fire while complicating detection and targeting. What changes with emerging technologies is the possibility that subterranean maneuver could move beyond static defense or slow siege tactics and become a method of operational breakthrough itself. The military that develops the ability to move quickly underground, creating routes where none previously existed, could bypass many of the assumptions dominating modern warfare today. Defensive belts, drone-covered kill zones, fortified trench systems, and heavily monitored front lines all depend on controlling movement across the surface. Subterranean maneuver has the potential to break that paradigm entirely and create a decisive advantage for the side capable of exploiting it first.

Even recent conflicts are reinforcing the incentive to move underground. During Operation Epic Fury, the vulnerability of U.S. expeditionary bases and regional infrastructure to long-range missile and drone attacks highlighted how exposed modern military power remains on the surface. Gulf states will increase investments in hardened facilities and buried energy infrastructure because they understand that refineries, command nodes, air bases, and logistics hubs are increasingly targetable. The more transparent and lethal the surface battlefield becomes, the stronger the incentive grows to move critical military functions underground.

The difference now is the possibility of industrializing subterranean maneuver through technology and autonomy. Luckey is not describing soldiers digging tunnels by hand. He is talking about autonomous subterranean systems capable of navigating underground independently. Machines moving beneath cities, borders, hardened military sites, and defensive belts while carrying sensors, explosives, communications equipment, electronic warfare systems, logistics, or potentially troops themselves.

The engineering challenges are severe. Global Positioning System (GPS) signals and many other satellite, radio, and electromagnetic-based systems do not function reliably underground. Radio frequencies degrade rapidly through rock, concrete, soil, and water, making communication extremely difficult. Most military systems built for surface warfare, from navigation tools to communications equipment to autonomous systems, simply do not work reliably beneath the Earth. Terrain density changes constantly. Heat management, structural collapse, groundwater intrusion, power generation, ventilation, excavation speed, and underground navigation all create major obstacles. Digging itself remains painfully slow compared to maneuver on the surface. Yet many of the same arguments once applied to submarines, aircraft, and armored vehicles. Early military technologies often appear impractical until operational necessity, competition, and war accelerate innovation far faster than peacetime assumptions predict.

Elon Musk briefly touched on part of this problem when he launched The Boring Company. Musk argued that modern tunneling technology still operates at the speed of a snail compared to what would be required for transformative infrastructure projects. He repeatedly discussed the need to dramatically increase excavation rates because humans remain surprisingly slow at moving underground. While his focus was commercial infrastructure and transportation, the military implications are obvious. If excavation speeds improve significantly, and if autonomous systems reduce risk and manpower requirements, the military problem set changes dramatically.

Imagine autonomous drilling systems inserted, even air-dropped, miles outside an enemy defensive zone, in neighboring countries, or launched from the sea. Instead of forcing passage through heavily defended terrain under constant drone observation, they tunnel beneath portions of it. Imagine systems capable of infiltrating sensors, explosives, communications nodes, supplies, or even troops underground while the defender remains focused on threats above ground. While Russian soldiers have already tried crawling through gas pipelines simply to avoid the lethality of the surface battlefield, future militaries may possess the ability to rapidly deliver vehicles, robots, explosives, sensors, and other capabilities underground with machines designed specifically for subterranean maneuver, creating pathways and avenues of approach that did not previously exist.

Modern militaries increasingly orient upward because of drones. Commanders scan rooftops, skies, electromagnetic signatures, thermal emissions, and satellite feeds. The surface battlefield grows more transparent and lethal every year. Underground maneuver attacks that entire current paradigms by exploiting the one area still extraordinarily difficult to monitor continuously: beneath the surface itself.

A global drone race is already underway as militaries rush to adapt to the transparency and lethality of modern battlefields. There is still time for a parallel subterranean race to emerge. The nation or military that recognizes where warfare is already heading and invests now in the technologies, engineering, autonomy, navigation, and doctrine required for underground maneuver could gain a decisive advantage before others fully understand the battlefield is already changing beneath their feet.

John Spencer is the Executive Director of the Urban Warfare Institute and a founding member of the International Working Group on Subterranean Warfare. He served twenty-five years as an infantry soldier, including two combat tours in Iraq. He is the author of Connected Soldiers: Life, Leadership, and Social Connections in Modern War, Understanding Urban Warfare, and 20 Times I Almost Died: Life Lessons from the Edge of Survival.

Learn more at www.johnspenceronline.com

X: @SpencerGuard

The views expressed in this article are the writer’s own.