A video of a mysterious aircraft thundering over a U.S. military installation has set off a wave of speculation online, and the leading theories all point to aircraft the Pentagon would rather nobody photographed.

The aircraft was captured flying over McConnell Air Force Base in Wichita, Kansas. It is believed to be the B-21 Raider, a nuclear-capable stealth bomber carrying a unit price tag of roughly $700 million.

That identification is unconfirmed. OutKick's David Hookstead, who first published the footage, wrote that a reflection off what appears to be a cockpit window around the seven-second mark is the strongest evidence for the B-21 - but allowed it could also be the RQ-170 Sentinel or the RQ-180, a classified surveillance drone whose existence the government has never acknowledged. Other observers have argued the shape is a better match for the older B-2 Spirit.

McConnell is a tanker base, home to the KC-46 Pegasus, and sits well outside the B-21's Edwards Air Force Base test corridor - which is part of why the sighting drew attention, and part of why some doubt the identification.

Witnesses on the ground said they felt the aircraft before they ever saw it.

"I never saw it, but I could hear it. It was shaking the ground! I've never heard anything like it," one X user wrote.

Northrop Grumman landed the contract to build the bomber in 2015 and the U.S. Air Force expects the Raider to enter operational service in the coming years. The first aircraft is slated to arrive at Ellsworth Air Force Base in 2027.

The Pentagon has signaled it wants at least 100 of the bombers, flying alongside a fleet of 76 modernized B-52 Stratofortresses. However, Defense Secretary Pete Hegseth has made clear the Pentagon may need far more firepower than that.

"We have to invest in more capabilities to include the B-21, which is ahead of schedule," Hegseth told the Senate Armed Services Committee in April. "We believe we will require a lot more - over 100 - in the future."