The US military has asked for the public's help to locate one of its $100m (£80m) F-35B fighter jets after the pilot ejected from the aircraft.
It went missing on Sunday afternoon when the pilot was flying over the southern state of South Carolina.
The pilot, who has not been named, ejected and parachuted safely. He is in a stable condition in hospital.
Officials said the aircraft was involved in a "mishap" but did not offer details of what that was.
It was left in autopilot mode when the pilot ejected, a spokesman at Joint Base Charleston told NBC News, adding that it may have been airborne for some time.
Officials said they were focusing their searches around Lake Moultrie and Lake Marion, north of the city of Charleston.
The search area was based on the jet's last known location.
Nancy Mace, a Republican congresswoman for South Carolina, asked on X, formerly Twitter: "How in the hell do you lose an F-35?
"How is there not a tracking device and we're asking the public to what, find a jet and turn it in?"
The aircraft is a stealth jet - meaning its airframe, sensors and systems are designed to operate undetected by enemy radar.
Joint Base Charleston posted its appeal for help on X. "Emergency response teams are still trying to locate the F-35," it said.
"The public is asked to co-operate with military and civilian authorities as the effort continues."
It encouraged anyone with information that could help its recovery teams to contact its operations centre.
Flight tracker Flightradar24 posted an image on X showing several aircraft scouring the area.
The Marine Corps said in a statement to the BBC its knowledge of the incident was "limited" at the moment, it was still trying to gather more information.
It added that the mishap would be "under investigation".
The jet costs around $100m, its manufacturer Lockheed Martin told the BBC.
A second F-35 flying at the same time returned safely to base, military spokeswoman Maj Melanie Salinas told Associated Press.
In 2018, the US military temporarily grounded its entire fleet of F-35 jets after a crash in South Carolina.