This program wasn't always classified - it started life as an open project, and later "went dark" when scavengers started showing up at Semipalatinsk - see this

This program wasn't always classified - it started life as an open project, and later "went dark" when scavengers started showing up at Semipalatinsk - see this blog posting from 2011: http://lewis.armscontrolwonk.com/archive/4021/tunnel-re-sealing-at-semipalatinsk http://lewis.armscontrolwonk.com/archive/4021/tunnel-re-seal... The same author as the original article here, Ellen Barry, actually wrote about this program back in 2011 too. So it hasn't been suddenly declassified.