The assumption for years has been that the Chinese arsenal is relatively small — anywhere from 80 to 400 warheads.
China has encouraged that perception. As the only one of the five original nuclear states with a no-first-use policy, it insists that it keeps a small stockpile only for “minimum deterrence.”
Given China’s lack of transparency, Karber argues, all the experts have to work with are assumptions, which can often be dead wrong. As an example, Karber often recounts to his students his experience of going to Russia with former defense secretary Frank C. Carlucci to discuss U.S. help in securing the Russian nuclear arsenal.
The United States had offered Russia about 20,000 canisters designed to safeguard warheads — a number based on U.S. estimates at the time.
The generals told Karber they needed 40,000.
Skepticism among analysts
At the end of the tunnel study, Karber cautions that the same could happen with China. Based on the number of tunnels the Second Artillery is digging and its increasing deployment of missiles, he argues, China’s nuclear warheads could number as many as 3,000.
It is an assertion that has provoked heated responses from the arms-control community.
Gregory Kulacki, a China nuclear analyst at the Union of Concerned Scientists, publicly condemned Karber’s report at a recent lecture in Washington. In an interview afterward, he called the 3,000 figure “ridiculous” and said the study’s methodology — especially its inclusion of posts from Chinese bloggers — was “incompetent and lazy.”
“The fact that they’re building tunnels could actually reinforce the exact opposite point,” he argued. “With more tunnels and a better chance of survivability, they may think they don’t need as many warheads to strike back.”
Reaction from others has been more moderate.
“Their research has value, but it also shows the danger of the Internet,” said Hans M. Kristensen of the Federation of American Scientists. Kristensen faulted some of the students’ interpretation of the satellite images.
“One thing his report accomplishes, I think, is it highlights the uncertainty about what China has,” said Mark Stokes, executive director of the Project 2049 Institute, a think tank. “There’s no question China’s been investing in tunnels, and to look at those efforts and pose this question is worthwhile.”
This year, the Defense Department’s annual report on China’s military highlighted for the first time the Second Artillery’s work on new tunnels, partly a result of Karber’s report, according to some Pentagon officials. And in the spring, shortly before a visit to China, some in the office of then-Defense Secretary Robert M. Gates were briefed on the study.
“I think it’s fair to say senior officials here have keyed upon the importance of this work,” said one Pentagon officer who was not authorized to speak on the record.
For Karber, provoking such debate means that he and his small army of undergrads have succeeded.
“I don’t have the slightest idea how many nuclear weapons China really has, but neither does anyone else in the arms-control community,” he said. “That’s the problem with China — no one really knows except them.”