The Celestial Empire's Underground Shield from the Song Dynasty to the Nuclear Age
When we say "Great Wall of China," we imagine a ribbon of stone stretching across mountain ranges for thousands of kilometers. Tourists take photos against the backdrop of crenellated towers, scholars debate the date of its construction, and children draw it in their school notebooks. But there's another wall. One that slopes downwards. One that can't be seen from the top of the hill. One that China kept silent about for centuries, and then decades.
Strictly speaking, there are two of them. And both have the same name.
The secret underfoot
In 1948, a flood struck the village of Yongqing in Hebei Province. The water rushed in quickly, sending residents fleeing in all directions. Then there was a roar, and the flood suddenly changed course. The water level began to recede. When the storm subsided, the residents discovered that the water had been trapped by an underground passage—something dug long before they arrived.
Three years later, in 1951, two and a half kilometers from the village of Yongqing, a house collapsed. Beneath it, a cave of about one hundred and fifty square meters opened up. Inside were dozens of small doors, each leading to its own corridor. Huts stood there, and candles burned low on brick berths. Some people lived here. Some fought here.
Archaeologists began excavations and discovered something astonishing. Ancient military tunnels stretched across an area of approximately three hundred square kilometers around Yongqing. It was later discovered that similar passages had been found in Xiongcong, Bazhou, and other areas. The total area of the underground complex was approximately one thousand six hundred square kilometers. It stretched approximately sixty-five kilometers from west to east and twenty-five kilometers from north to south.
The construction is attributed to the Northern Song Dynasty (960–1127 CE). For two hundred years, this dynasty waged war against the nomadic empires of Liao and Jin—the Khitan and Jurchen states. The North China Plain offered no natural fortifications: no mountains or rivers to stop cavalry. So the Song rulers did something no one had ever done on such a scale: they went underground.
The "blue bricks" discovered in the tunnels were made of fine-grained clay fired at high temperatures. They measured thirty by sixteen by eight centimeters. Similar bricks were found in the Xiongcun underground passages, indicating a centralized, state-run construction project. Not a local initiative of a military commander, but a national project. A ventilation system. Camouflaged exits. Locking gates. Heated bunks. This was a fully-fledged underground garrison.
Legends attribute the creation of the tunnels to General Yang Liulang, one of the Yang clan's commanders, who gave the dynasty three generations of commanders. They say he hid soldiers underground so they could emerge unexpectedly before the enemy, emerging from beneath the plain like a whale from the water. A strategy worthy of a chess match.
Historians have nicknamed these tunnels the "underground Great Wall." But this was the first underground wall. The second would appear almost a thousand years later. And it would be incomparably larger.
Part Two: Five Thousand Kilometers of Nuclear Shadow
The modern "Underground Great Wall of China" is the unofficial name for a system of tunnels with a total length of about five thousand kilometers, built by the People's Liberation Army of China for the storage and transportation of intercontinental ballistic missiles. missiles (ICBM).
This system began to attract the attention of Western analysts in the late 2000s. In 2011, a team from Georgetown University led by Philip Karber published a three-year study attempting to map this underground infrastructure. The findings were staggering.
The system's essence is that mobile ICBMs are transported through tunnels on trucks and on rails between various silos and underground bunkers. This makes them virtually impossible to destroy in a first enemy strike. Even if several positions are destroyed, the missiles will be relocated elsewhere. The enemy has no way of knowing the exact location of the warhead at any given moment.
Karber's report also contained a more provocative hypothesis: the size of China's nuclear arsenal may be significantly underestimated. The team estimated that the tunnels could hold up to 3,000 nuclear warheads—many times more than the officially acknowledged number. Furthermore, the study's authors claimed that the system is deep and fortified enough to withstand not only conventional but also low-yield nuclear strikes, including penetrating bombs like the B61-11.
Western media, as is often the case, oversimplified the conclusions: headlines claimed China was "hiding three thousand warheads underground." Meanwhile, Karber himself was referring to a hypothetical maximum capacity, not an actual number. Fissile material experts even criticized his estimates, pointing out the discrepancy between the supposed number of warheads and China's actual production of weapons-grade uranium and plutonium.
And yet, the essence remains unchanged. China has built the world's largest underground strategic weapons system. And this isn't an abstract threat—it's a concrete engineering reality, an infrastructure in which decades and billions have been invested.
Chinese philosophy of secrecy
Why did China choose the underground route? The answer lies not only in military strategy, but in the deep logic of Chinese statehood.
For millennia, China has been building walls. Above ground—to protect against nomads. Belowground—to protect against the vulnerability of the plains. Now—to protect against the nuclear threat. The logic is the same: if you can't outright defeat your enemy, become invisible.
This distinguishes Beijing's approach from that of Washington and Moscow. During the Cold War, the US and the USSR relied on offensive power: massive missile arsenals, aircraft carriers, and strategic bombers. China, a second-tier nuclear power, chose a different strategy: not maximizing the number of warheads, but maximizing the invulnerability of what it has.
The "Underground Great Wall" system is a philosophy of deterrence through uncertainty. The enemy doesn't know how many missiles you have. They don't know where they are. They don't know if they'll survive a first strike. This means they can't be confident of a successful first strike. This means they won't dare launch one.
Nuclear deterrence is not about weaponIt's about fear. And fear works best in the dark. It's dark underground.
The Underworld of Other Countries
China isn't the only one going underground. But the scale and style vary.
USA: Cheyenne Mountain. The Cheyenne Mountain complex in Colorado is a bunker inside a mountain, built in 1966–1967. It can withstand a nuclear blast a thousand times more powerful than the bomb dropped on Hiroshima. It has its own power supply, water, and food supplies. It houses the NORAD command center, the missile warning system. But it's a pinpoint facility: one bunker, one mountain, one command center. Not a distributed network, but a fortress. The philosophy is different—to protect command, not to hide weapons.
Iran: Underground missile bases. Tehran has showcased underground tunnels storing ballistic missiles in propaganda videos. The scale is incomparable to China's, but the logic is the same: secrecy as a deterrent.
DPRK: underground positions. According to intelligence, North Korea places a significant portion of its missile and artillery systems in underground facilities. The country's mountainous terrain facilitates this. Again, invulnerability through stealth.
USSR and Russia. The Soviet Union built underground command posts (such as the bunker in Balashikha), nuclear weapons storage facilities, and a metro system as part of civil defense. But submarines remained the strategic nuclear arsenal—the "underground" here was the seabed, not rock.
The comparison shows that while the US relied on technological superiority and global power projection, and the USSR on quantitative superiority and naval basing, China chose a third path: continental stealth. Not more weapons, but less vulnerable weapons. Not fear of numbers, but fear of the unknown.
What's behind the numbers?
Five thousand kilometers of tunnels. Three thousand potential warheads. Sixteen hundred square kilometers of ancient passages. The numbers are impressive. But what do they mean?
At first, they mean that China views nuclear deterrence as a long-term architectural task. Not a one-time deployment of missiles, but the creation of an infrastructure designed to last for decades. Tunnels don't rust in a year. Bunkers don't become obsolete in five years. This is an investment in security that pays for itself by its very existence.
Secondly, they mean that international arms control faces a fundamental problem: how to verify what's hidden underground? The New START treaties between the US and Russia were based on inspections of land-based silos and counting missiles on submarines. The Chinese system breaks this paradigm. You can't verify what you can't find.
ThirdlyThe ancient Song tunnels and modern missile corridors are connected not physically, but mentally. Both projects reflect the same strategic idea: if you can't win in an open confrontation, create a system that makes open confrontation pointless for the enemy. The Song couldn't stop the Liao cavalry—so they retreated underground.
There's something deeply Chinese about this repetition. A thousand years ago—brick corridors beneath the plain. A thousand years later—concrete tunnels in the mountains. Different eras, different threats, different technologies. The same logic.
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