The most widely discussed framework proposes that at least some UAP are physical craft or manifestations of non-human intelligence — entities that did not originate from human civilisation. This encompasses the classic Extraterrestrial Hypothesis (craft from other star systems), the Ultraterrestrial Hypothesis (non-human intelligences local to Earth but not human), and the Cryptoterrestrial Hypothesis (a hidden indigenous population, possibly subterranean or aquatic). Jacques Vallée's Control-System Hypothesis also falls here: the idea that the phenomenon, whatever its substrate, operates as a sociological conditioning mechanism shaping human belief over long timescales. The common thread is that the intelligence behind UAP is not us.