A pilot training in one of America's most expensive weapons systems ejected over South Carolina. Officials can't find the F-35 he was flying.

• A pilot ejected from his F-35B Lightning II jet after a "mishap" during a Sunday training flight.
• While the pilot was unharmed, the jet was lost and has not yet been recovered by officials.

An expensive F-35 jet has been lost somewhere in South Carolina following a training mishap.

A Marine Corps pilot was flying one of the country's most expensive fighters near Joint Base Charleston on Sunday afternoon when an unknown problem occurred, forcing the pilot to abandon the aircraft and eject.

"We can confirm a mishap involving an F-35B Lightning II jet from Marine Fighter Attack Training Squadron (VMFAT) 501 with the 2nd Marine Aircraft Wing," a United States Marine Corps spokesperson told Insider. "The pilot safely ejected from the aircraft. We are currently still gathering more information and assessing the situation. The mishap will be under investigation."

The F-35 Lightning II Joint Strike Fighter program is the Department of Defense's most expensive weapon-system program, according to the US Government Accountability Office. Officials estimated it would cost American taxpayers about $1.7 trillion to "buy, operate, and sustain the aircraft and systems over its lifetime," the GAO reported. A 2020 report from the Project On Government Oversight found a single Marine Corps F-35B cost $135.8 million.

The pilot, after ejecting, was found in a residential neighborhood near South Kenwood Drive in North Charleston and transported to a local medical center in stable condition, the local news outlet WCBD reported. His wingman safely landed in a separate aircraft, the outlet reported.

Representatives for Joint Base Charleston did not immediately respond to a request for comment from Insider but posted on X that officials were working with Marine Corps Air Station Beaufort to locate the lost F-35. Details regarding the training exercise that prompted the mishap are under investigation.

A former test pilot said F-35 jets — Lockheed Martin's fifth-generation stealth aircraft — were intended for air superiority and strike missions and were "designed precisely" to fight and win in the kind of war happening in Ukraine, Insider previously reported. The US Air Force deployed F-35s to NATO's front line to patrol for Russian missiles following the invasion of Ukraine.

While each aircraft has various weaponry configurations, the jets have a powerful electronic intelligence, surveillance, and reconnaissance suite. In a configuration known as "beast mode," which Insider previously reported sacrifices stealth for firepower, F-35s can be equipped with laser-guided bombs on their wings and an AIM-9 air-to-air heat-seeking missile.