Kazantsev pointed out that the facts suggested a nuclear airburst. Perhaps it was a deliberate detonation by aliens, to demonstrate atomic power to Earthlings. Or it might have been the accidental explosion of a nuclear starship drive. In an accidental crash, a socially advanced alien pilot would naturally guide his stricken craft to one of the planet’s "poles of uninhabitedness." And eyewitness reports made it clear that the Tunguska body had definitely changed course in flight!