The U.S. Navy reportedly identified the mysterious white plane spotting circling over the Denver metro area Wednesday as a Navy E-6B Mercury.

Navy Lt. Leslie Hubbell told The Denver Channel on Thursday that the plane was created by Boeing at an estimated cost of $141.7 million per unit. Hubbell said the plane’s mission is classified.

"The overall mission of the E-6B is command, control and communications abilities to direct and employ strategic resources," Hubbell said.

An E-6B plane is a large, high-tech aircraft that can communicate with important assets such as nuclear submarines and is built with a system that can launch intercontinental ballistic missiles.

Hubbell said the plane was circling over Denver because it wasn’t granted clearance by the FAA to land at Tinker Air Force Base in Oklahoma where it was housed. The plane was at Travis Air Force Base where planes of that caliber are routinely serviced, according to the station.

However, Travis Air Force Base officials declined to say whether the plane had landed there and FAA officials said it had no contact with the mysterious aircraft.

An unnamed federal official gave a different story to the station.

The high-ranking official, who spoke to The Denver Channel on condition of anonymity, said the plane was involved in a classified training mission. The official said the mission involved electronic surveillance.

It’s unclear what kind of surveillance mission the plane would be on, but the official said the kind of missions aren’t uncommon and the public isn’t usually aware of training missions.

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