The article says that the tunnels were dug by the Second Artillery Corps, which is a a top secret division of the Chinese military in charge of nuclear deployment. The Washington Post article added that the students research is the 'largest body of public knowledge' on the tunnel network. The study was done in 3 years.
The yet unpublished 363-page study is being circulated among top US defense officials including the Air Force Vice Chief of Staff. An unnamed Defense Department strategist has been quoted as saying, "It"s not quite a bombshell, but those thoughts and estimates are being checked against what people think they know based on classified information."
The research reports have drawn a lot of flak over the methods used to collect information. They have supposedly used internet-based sources like Google Earth, blogs, military journals and even a fictionalised Chinese TV show. The Post added that the students were able to acquire a 400-page manual produced by the Second Artillery that was only exclusively available to Chinese military personnel.
The Washington Post stated that the students" professor, Phillip Karber was a top strategist during the Cold War, who reported directly to the secretary of defense and the chairman of the Joint Chiefs of Staff. Karber commented on the invention of the tunnels, China could have 3,000 nuclear warheads much higher than estimates which are in the range of 80 to 400.
US officials refused to comment on the report.