Place this one in the strange but true category? The military subterrene! An urban legend? Combat Mole?
"Subterrene . . . is a vehicle that travels underground (through solid rock/soil) much as a submarine travels underwater, either by mechanical drilling, or by melting its way forward."
From some Russian sources:
"The Soviet Union was doing its best to achieve as much technological progress as possible. The ultimate goal was to make science fiction reality. Telepathy, amphibious boats capable of "navigating" under the ground, space planes - all these projects used to be developed in the USSR."
"Battle Mole, the secret subterrenes"
"USSR Battle Mole – This is probably an urban legend, because all sources are very unreliable and controversial.. According to some authors, Soviet Union like Nazi Germany and the USA had projects of Subterrenes in 1930s and 1960s."
This is a prototype of Combat Mole? Not a full-sized machine as proposed? Digger was to be thirty-five meters long? Click on image to see an enlarged view. Atomic powered also?
Atomic-powered digger was tested [prototype?] but the project cancelled because of an INCIDENT!
I might well imaginethe INCIDENT some sort of unreported nuclear meltdown and large release of radioactive particles into the environment. A spew deadly to life forms.