The impending sea trials of China’s first aircraft carrier set commentators abuzz in the West and Asia over the past couple of months. I weighed in myself. And for good reason. The cruise of the yet-to-be-officially-named flattop, which finally took place last week, heralded a decisive break with the People’s Liberation Army Navy’s Maoist past as a coastal defence force. This is a development worth exploring in detail. As it happened, the Naval War College also convened its first Asian Strategic Studies Conference in Newport last week, in conjunction with the American Enterprise Institute and the Journal of Strategic Studies. My assigned topic was to determine whether there exists a common Asian culture of sea power (no, say I) and how influential the Western canon of maritime theory is among seafaring Asian nations (very, mainly by default).

To me, though, the most provocative presentation delivered at our conference related not to the sea but to the future of China’s land-based nuclear arsenal. In March 2008, China’s state-run CCTV network broke the news about a 5,000-kilometre-long network of hardened tunnels built to house the Chinese Second Artillery Corps’s increasingly modern force of nuclear-tipped ballistic missiles. Tunnelling evidently commenced in 1995. Located in, or rather under, mountainous districts of Hebei Province, in northern China, the facility is reportedly hundreds of meters deep. That makes it an exceptionally hard target against conventional or nuclear counterstrikes.China Defense Daily, a publication of the People’s Liberation Army (PLA), confirmed the CCTV account in December 2009.

What should have been a blockbuster story occasioned barely a peep in the Western press, and elicited little response even in Asia. For lack of a catchier metaphor, call it the dragon that never roared. The most prominent outlet to report on what Chinese pundits dubbed the ‘underground Great Wall’ was Chosun Ilbo, in South Korea. The Washington-based Jamestown Foundation’s China Brief covered the story shortly afterward. That was basically it for original reporting. The story isn’t so much that Beijing has constructed hardened sites to safeguard its missile force. An invulnerable second-strike capability has been the gold standard of nuclear deterrence since the early Cold War. In theory, a military able to ride out an enemy first strike with a substantial portion of its missile force intact can deter such an attack. No sane adversary would launch a first strike if it knew its actions would summon forth a cataclysmic reply.

A more survivable nuclear deterrent, then, should bolster strategic stability between China and the United States. China has long contented itself with a ‘minimalist’ deterrent posture, fielding a small, rudimentary force of intercontinental ballistic missiles. The logic of minimalism—sound in my view—is that so long as even a single missile survives to retaliate against an enemy’s homeland, that adversary will desist from actions China deems unacceptable. Estimates of the total number of Chinese warheads even today, well into Beijing’s nuclear modernization effort, generally range from 150 to 400 devices. Even in this age of renewed US-Russian arms control, this remains a modest force. But minimal deterrence could employ a more robust force than the People’s Liberation Army fielded in past decades. ‘Minimal’ is a squishy term. Furthermore, Chinese officials and pundits have taken to debating adopting a ‘limited deterrent’ strategy. ‘Limited’ too remains hazily defined.

The very scale of the underground network opens up new vistas for Chinese nuclear strategy. The presenter at our conference reported piecing together various bits of data, and concluding that China may have constructed a far larger warhead inventory than most estimates hold. He projected an upper limit of 3,600 doomsday devices and delivery platforms, namely ballistic missiles of various types. The underground Great Wall could presumably accommodate such a force with ease. At a minimum, it presents Beijing new options. Think about it. The ‘New START’ accord inked by US President Barack Obama and Russian President Dmitry Medvedev last year limits US and Russian nuclear forces to 1,550 deployed warheads apiece. Because of the fudge factor often built into international treaties, notes the Federation of American Scientists, the actual numbers permitted under New START come to over 2,000 warheads for each side.

Even so, if the PLA has covertly departed from minimal deterrence—secreting hundreds of new weapons in the Hebei tunnel complex—then it could upend the strategic balance overnight, achieving parity or near-parity with the United States and Russia in deployed weaponry. I’m not sure how much of this to credit, and the presenter freely admitted that there was a significant guesswork quotient in his figures. But then there was a significant guesswork quotient to the long-running speculation surrounding the Chinese aircraft carrier project, a project of far smaller consequence than a clandestine Chinese nuclear build-up. At a minimum it would be worthwhile to inquire into the veracity of Chinese reporting on the underground Great Wall, and to ponder the implications if reports are accurate. Let the debate begin—at last.

James Holmes is an associate professor of strategy at the US Naval War College and co-author of Red Star over the Pacific. The views voiced here are his alone.