" Either it was general reconnaissance ahead of a further incursion at a future date, in which case it had likely involved cameras and thermal imaging and ground-penetrating radar, or it was the actual search for Keever itself, which they had long predicted would include the air, in which case it would involve pretty much the same technology, but it would find nothing either, because of the hogs. "

― Lee Child , Make Me (Jack Reacher, #20)