Japan has 13 operational F-35s, with nearly 150 more on order. The planes are based with the 302nd Squadron at the Misawa Air Base in Aomori, northern Japan

A Japan Air Self-Defence Force spokesman has confirmed to Sputnik that one of its F-35s has gone missing with one pilot said to be on board. "It disappeared from radars," the spokesman said, adding that a search for the plane is underway.

Earlier, Japanese national broadcaster NHK reported that an air force F-35A disappeared from radar screens during a routine training flight.

According to the military, ground control lost contact with the plane at around 7:27 pm on Tuesday, about 135 km northeast of Misawa city, during training. The plane is believed to have one pilot onboard.

Over a dozen Maritime Self-Defence Force patrol aircraft and escort vessels are engaged in a search operation, NHK said, with the local Coast Guard also deploying two patrol vessels to help in the search.

Ten F-35As were delivered to the Misawa Air Base last last year.

All JASDF F-35As Grounded

Later Tuesday, Japanese Defence Minister Takeshi Iwaya said that the air force would suspend flights of its remaining F-35As for the time being following the plane's disappearance, Kyodo has reported.

Tokyo ordered a total of 42 F-35As in late 2011, with the existing order updated to include 63 more F-35As and 42 F-35Bs by late 2018, with Japan becoming the second-largest buyer of Lockheed Martin's fifth generation stealth fighter.

Last September, the US military grounded its entire fleet of F-35s in the wake of a Marine Corps F-35 crash in South Carolina. That incident followed reports in late 2017 that a US F-35 deployed in Okinawa, Japan lost part of its fuselage in mid-air during a routine training mission.

The F-35 program is one of the most expensive defence projects in history, with a projected total cost of $1.5 trillion over its 55 year lifespan. In addition to cost (currently ranging from $89.2-$115.5 million apiece), the plane has been criticised for a plethora of glitches and design flaws which continue to plague it over four years after its introduction with the US military in 2015. Acting US Defence Secretary Patrick Shanahan has reportedly described the plane as "f***ed up," with President Donald Trump repeatedly criticising it as an example of Pentagon waste on the campaign trail.

Last month, a US defence spending watchdog complained that the new F-35s for the US Navy were nowhere near operational status, emphasising that the plane was "not ready to face current or future threats" and could put US military personnel's lives at risk.