The military has ever been interested in the Crop Circles. They are even used as training markers for helicopters. Rumor has it that specially equiped helicopters should be able to see the Crop formation before they fully materialise in the field. This would be possible due to some sort of infrared devise that reads the signature of the initial groundwork. At this point we are unable to be 100% sure about this theory but all the clues lead in this direction. We know for a fact that the extraterrestrial formations are not always created in one session. Often additional circles or elements present themselves days after the first creations appeared. It is therefore safe to say that certain invisible parts could already be there and detectable by certain technology.