Astral Projection

Some military strategists in classical China apparently used the astral planes to their advantage, accessing it either through sleeping and dreaming or through meditational practices that permitted them to project their astral bodies into enemy territory and spy upon them.

The CIA carried out various investigations in the mid 20th century investigating such claims using psychics under laboratory conditions. These documents were (in part) released to the public later on, although it is not clear to what degree the CIA was successful with these experiments.