Japan's Defense Ministry says an F35A fighter jet that crashed into the sea off northern Japan on Tuesday had made two emergency landings in the last two years.
State Minister of Defense Kenji Harada was speaking at a Lower House committee meeting on Thursday.
The minister referred to a test flight by US manufacturer Lockheed Martin in June, 2017, before Japan deployed the aircraft. He said the flight was aborted after a cooling system alert.
The minister said the manufacturer found faults in the system and replaced the defective parts before delivering the jet to the defense ministry.
A ministry official also said at the committee meeting that while the same aircraft was flying in bad weather last August, there was a malfunction in the position indicator.
The Defense Ministry says the defective parts were replaced.
The Air Self-Defense Force began deploying F35A jets at its Misawa base in Aomori Prefecture, northern Japan, in January last year.
The ministry official told NHK that it's not known whether the two incidents were linked to Tuesday's crash.