There’s been much media coverage recently focusing on China’s network of underground tunnels that have been built to protect its nuclear deterrent. However, contrary to the impression that may have been given, this so-called “Underground Great Wall” isn’t a new or secret military project. It was in fact revealed by China as early as the mid-1990s. Clear images of this project appeared on China’s most popular official TV programs and spread widely among Chinese internet users.
The decision to undertake the project, which is aimed at building highly secure underground facilities for China’s nuclear forces, was made in the late 1970s. Built in mountainous areas in China, the Underground Great Wall has the capacity to provide protection for strategic missiles of the Second Artillery, which operates China’s land-based nuclear arsenal. Beginning in the late 1970s and early 1980s, construction (part of it at least) was declared complete in 1995 by Jiefangjun Bao (People’s Liberation Army Daily).
In the years that followed, official press reports offered more detailed insights into this project. For example, in 2008, an official TV program “Junshi Jishi” (Military Documentary) broadcast a documentary that revealed the construction of underground missile silos in the Kunlun Mountains in 2006 and 2007 by an engineering unit of the Second Artillery. This was widely interpreted by foreign analysts as a signal that the Underground Great Wall had been extended to the Qinghai-Tibet Plateau. The bulk of the project, however, is believed to be located somewhere in northern China, where more than 5,000 kilometers of underground tunnels were reportedly built in the mountains.
The tunnels are reportedly hundreds of meters underground. Apparently, China has invested heavily in this massive project, and seeks to protect its nuclear assets from not only conventional strikes, but also nuclear strikes. China’s decision to publicize its progress over the project is a classic strategy: make one’s capabilities known to potential adversaries to discourage a first strike.
The Underground Great Wall underscores Beijing’s decision to consolidate its existing nuclear arsenal by investing heavily in massive tunnels. China could have chosen to significantly expand its nuclear arsenal by buying and deploying many more nuclear weapons and delivery vehicles, something that would have been easier, cheaper, and more effective in building a massive nuclear capability. But in terms of offensive-defensive balance, the nuclear world now is a defense-dominant one. Under such a system, highly-survivable nuclear capabilities contribute to stability by reducing the incentive of both players to act preemptively during a crisis.
In addition, confidence in the survivability of one’s nuclear forces helps to ease the urge to engage in an arms race. For China, which is concerned about its second strike capability, investing in tunnel building is actually a much more stabilizing posture than building up a nuclear arsenal. From the standpoint of preserving deterrence, if all nuclear weapons states shifted their nuclear posture to concentrating on improving the survivability of smaller arsenals, it would be much easier to maintain strategic stability and to achieve deep nuclear cuts.
Still, there are two potential concerns when it comes to China protecting its nuclear forces in robust underground facilities for strategic stability. First, this will make U.S. damage limitation operations extremely difficult. As the survivability of China’s mobile missiles increases through enhanced transportability, the Underground Great Wall greatly reduces the vulnerability of the rest of the less-mobile missiles. The fact that preemptive strikes against China’s nuclear forces for the purpose of damage limitation are becoming increasingly difficult might concern some U.S. strategists who still see value in damage limitation operations.
Another potential concern is that the Underground Great Wall may reduce the capacity of other countries to monitor China’s nuclear development and deployment, which might generate anxiety and have an adverse impact on confidence building. Of course, it’s difficult to know how much the U.S. and other governments really know about China’s nuclear arsenal – it’s possible to glean information from purchases of materials, for example. But although anxiety is likely to be compounded by the fact that China’s confidence in its second strike capability is increasing, there are signs that China may be more open to verification measures. Chinese participants in recent track two bilateral security dialogues, for example, have shown interest in participating in transparency and verification measures that they once vehemently opposed.
The reality is that greater transparency and more effective confidence building may be easier when both parties are no longer concerned about their second strike capabilities. Critics of the Underground Great Wall therefore fail to appreciate that the Chinese posture could actually be stabilizing rather than destabilizing. And as China becomes more confident, we might be able to expect a more transparent nuclear posture.
Tong Zhao is a PhD Candidate in International Affairs, Science and Technology at the Sam Nunn School of International Affairs.