The existence of UFOs, i.e. vehicles of an extraterrestial nature, is proven by verifiable scientific methods before January 1, 2000. Methods of verification include, but are not limited to:
Judgement will be based on information available from established scientific newsmedia, e.g. Scientific American
In view of the last UFO flap over Mexico (very convincing video footage), the very well-documented flaps in Belgium and the film about the dissection of an alien I think the claim may be true. Many people have seen things which can at present not been explained. BUT: the scientific media are silent about these events, the extraterrestrial nature is not proven yet ...