The US Navy has confirmed videos taken by their pilots showing three encounters with UFO s are authentic.
Footage showing the strange objects manoeuvring at high speed was never meant to be released publicly, it has emerged.
The first video was taken in 2004 and shot by the F-18's gun camera, while the second and third clips were both recorded on the same day in 2015.
The pilots described what they saw as "unidentified aerial phenomena" in the videos, originally published by the New York Times.
A leaked report from the Pentagon quoted some of the pilots as saying the UFOs could make themselves invisible when near the war planes.
The craft were described by the pilots as "solid, white, smooth, with no edges" and looked like "an elongated egg or Tic Tac".
On Tuesday, Navy spokesman Joseph Gradisher made a statement confirming the sightings.
"The Navy considers the phenomena contained/depicted in those three videos as unidentified," Mr Gradisher told The Black Vault , a website dedicated to declassified government documents.
"The Navy has not publicly released characterisations or descriptions, nor released any hypothesis or conclusions, in regard to the objects contained in the referenced videos."
He added: "The 'Unidentified Aerial Phenomena terminology is used because it provides the basic descriptor for the sightings/observations of unauthorized/unidentified aircraft/objects that have been observed entering/operating in the airspace of various military-controlled training ranges."
In June, three US senators were reportedly briefed by the Pentagon about recent reports detailing UFO sightings by Navy pilots.
US president Donald Trump had also been briefed on the encounters.
Senator Mark Warner, vice chairman of the Senate Intelligence Committee, confirmed with Politico that he was at the briefing.
Rachel Cohen, his spokesperson, told Politico: "If naval pilots are running into unexplained interference in the air, that’s a safety concern Senator Warner believes we need to get to the bottom of."
