TOKYO — Japan’s first three F-35B stealth fighter jets arrived Thursday at an air base in the south of the country, its latest move to fortify defenses as tensions in the region grow.

The new arrivals are three of the four F-35Bs scheduled for deployment at the Nyutabaru Air Base in the Miyazaki prefecture. The fourth jet is set to arrive at a later date, the Air Self-Defense Force said.

The jets, which have short take-off and vertical landing functions, are to operate from two Japanese helicopter carriers, the Izumo and the Kaga, that were modified to accommodate the F-35B.

The Defense Ministry has said four more F-35Bs will be delivered to Nyutabaru by the end of March 2026.

Japan considers China as a regional threat and has accelerated its military buildup on remote islands in the southwest.

Separately on Thursday, a F-2A single-seater fighter jet crashed in the Pacific off Japan’s eastern coast during a training flight, but the pilot was rescued alive after he ejected himself in an emergency, according to the ASDF. It said that training flights for the aircraft have been suspended for safety checks.

Japan is currently constructing a runway on a new air base on the island of Mageshima, 160 kilometers (100 miles) south of the Nyutabaru base, for F-35B flight exercises. However, the drills will have to be conducted at Nyutabaru until around 2030 due to construction delays, triggering protests from local residents concerned about aircraft noise.

Japan plans to deploy a total of 42 Lockheed Martin F-35Bs and 105 of the conventional take-off and landing, or CTOL, F-35As, making the country the biggest F-35 user outside of the United States.