The US Department of Homeland Security has recorded a four-minute video of a mysterious object.
The footage, which was investigated and released online by a group known as the 'Scientific Coalition for Ufology', shows a peculiar object moving at speed over fields, roads and open water.
The incident is believed to have occurred on the morning of April 25 2013 at the Rafael Hernandez Airport in Aguadilla, Puerto Rico. The thermal camera footage was recorded by the crew of a DHC-8 Turboprop aircraft from US Customs and Border Protection.
The group responsible for releasing the footage claims to have spent two years investigating it with the co-operation of several prominent scientists before finally making it available to the public.
"Assuming the video isn't a clever hoax - which is always a possibility these days - it's a fascinating piece of footage," said Nick Pope, former UFO investigator for the British Ministry of Defence.
"About the only conventional explanation that might fit the bill is that this is some new drone, but the entry and exit from the sea and the apparent splitting in two of the object makes even this explanation seem unlikely. I'll be watching developments on this one with interest."