A video that has allegedly been leaked from the U.S. Department of Homeland Security (DHS) appears to show a UFO being tracked by a thermal imaging camera.

The video is almost four minutes long and UFO and alien researchers are calling it legitimate, The Express reports. The group responsible for posting the video online is the Scientific Coalition for Ufology (SCU).

SCU researchers say on their website that the flying object "exhibits characteristics that cannot be explained by any known aircraft or natural phenomenon."

The source of the video is said to be the DHS, which captured the video using a camera on one of their aircrafts.

The SCU is claiming a DHS whistleblower released the video and several witnesses came forward to report the unusual video. All of the witnesses are said to have requested anonymity.

It took quite some time for the group to come forward since the video was taken over two years ago. SCU investigated the video before releasing a 161-page report on their findings and coming out to the public. Six scientists and researchers were part of the lengthy research process.

The event that supposedly shows a UFO began on April 25, 2013 at about 9:20 p.m. at the Rafael Hernandez Airport in Aguadilla, Puerto Rico. A crew in a DHC-8 turboprop aircraft from the US Customs and Border Protection (CBP), which is part of the DHS, monitored the suspected UFO.

The object seen on the video looks like it is moving very fast over the land before heading into the ocean. It also appears to change shape or tumble.

A former investigator of UFOs for the Ministry of Defense, Nick Pope, finds the video interesting.

"Assuming the video isn't a clever hoax -- which is always a possibility these days -- it's a fascinating piece of footage," Pope said.

"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."

Pope said he plans to keep an eye on the developments surrounding this video.

Watch the video below. Do you believe it is a UFO or something else?