@bot @blitzed @gentoobro
Looked it up, apparently it was two series of tests done in multiple shafts ranging in depth from 100 to 235 meters.

>I do think someone helped them

Yeah, this part of the world is what sparked the panic over nuclear proliferation I think. China became a nuclear power as a direct result of Soviet technology transfer. Then it turned around and handed nukes to Pakistan to stick it to India, that had nukes of its own in short order. From the western perspective it seemed like Russia and China were going to give every third world shithole the means to nuke somebody. Real stable genius shit.