When the F-35 disappeared over South Carolina on Sunday, Joint Base Charleston (JBC) issued a plaintive call on social media asking for anyone who had information to call in.

The JBC said that "based on the jet's last-known position" the search was centered around two large lakes north of Charleston, suggesting it may have crashed.

The F-35 Lightning II jet is coveted by US allies around the world, especially Ukraine, with its distinctive shape and features that shield it from radar detection.

But the fate of the missing aircraft remained unclear on Monday.

"We are currently still gathering information. The investigation is ongoing," a JBC spokesman told AFP.

The pilot ejected for unknown reasons and parachuted safely into a North Charleston neighborhood -- leaving the jet flying in what some called a "zombie state."

In 1989 the pilot of a malfunctioning Soviet MiG-23 ejected over Poland and the jet continued to fly on autopilot until it crashed in Kortrijk, Belgium, more than 900 kilometers (560 miles) away.

The disappearance of a highly advanced aircraft that costs at least $80 million sparked incredulous comments online.

"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?" said Nancy Mace, a member of Congress representing the Charleston area.

- Still looking -

Some posted manipulated photographs of lost signs on trees, offering rewards to find the missing jet.

One post showed Ukraine President Volodymyr Zelensky posing in front of an F-35, suggesting he took it.

Since Russia invaded his country last year, Zelensky has been pressing the United States to supply his air force with the jet to give his military an advantage.

The missing aircraft was an F-35B, a variation operated by the Marines that has short takeoff and vertical landing capabilities.

The shape of its airframe, including two angled stabilizers on the back, and the use of special materials, make it harder to detect by traditional radar.

"Integrated teams are searching and preparing for the recovery of the jet," Joint Base Charleston said on social media as the hunt continued through Monday.

JBC spokesman Jeremy Huggins told the Washington Post that the jet's transponder was not working, and that its stealth capabilities added to the challenges of tracking it.

At least seven F-35s have been destroyed in previous crashes, due to a range of causes.