 The Soviet Union is purported to have built such a "battle mole", which operated until its onboard reactor failed.On line information presents research that was funded by the United States Government for the Los Alamos Scientific Laboratories University of California, Los Alamos, New Mexico for a project Camelot under the heading Systems and Cost Analysis for a
Nuclear Subterrene Tunneling Machine.A patent was subsequently issued under number 3,693,731 on September 26, 1972.