An F-35A stealth fighter that crashed in the Pacific during an exercise this week did not send an emergency alert, the Air Self-Defense Force said Thursday.

The single-seat jet had a system that would have emitted distress signals if the pilot ejected from the cockpit with a parachute, the ASDF said.

Search operations for the pilot — a major in his 40s — by the Self-Defense Forces, the Japan Coast Guard and U.S. forces have been continuing since the airplane disappeared from radar off the coast of northeastern Japan on Tuesday night.

The Defense Ministry has concluded the cutting-edge fighter crashed — citing wreckage from its tail being found in the sea — making it the first crash involving an F-35A worldwide.

The jet disappeared when flying with three other aircraft at distance for an air-to-air combat exercise, about 25 minutes after taking off from Misawa Air Base in Aomori around 7 p.m. Tuesday, according to the ASDF.

Shortly before it dropped off the radar, its pilot radioed the other three to say he was about to pull out of the drill, but none witnessed the plane crash, the ministry said.

Co-developed by nine countries including the United States and the U.K., F-35s are produced by U.S. defense company Lockheed Martin Corp.

Before the incident, Japan decided to purchase 105 F-35As from the United States, including those that have already been deployed.