Officials said that a Black Hawk helicopter carrying 10 crewmembers was believed to have crashed in the sea. They found an unused lifeboat and other fragments, including a door.
The Defense Minister Yasukazu Hamida told reporters, while struggling to keep back the tears, that no crew member had been located as the search continued on Friday.
He took the accident very seriously. He said that he would do his best to rescue the 10 missing people, and continue to collect information about the extent of the damage.
According to Yasunori Morishita, the chief of the Ground Self Defense Force (GSDF), the UH-60JA Black Hawk disappeared on Thursday afternoon, while it was on a recon mission in Japan's south islands.
The plane disappeared from radar 10 minutes after leaving a Miyako Island base. It is believed that it crashed in the water between Miyako Island and Irabu Island, which lies to the north-west. This area is located about 1,800 km (1,120 miles), southwest of Tokyo.
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Army officials reported that coast guard patrol ships discovered an unused lifeboat with a serial number matching the helicopter's missing aircraft and a door thought to be from the same aircraft, near the suspected crash site.
Japan has aggressively built up its defense capabilities in its southwest islands as a response to China’s increasing assertiveness in the region. This includes near Taiwan.
Morishita reported Thursday night that the helicopter was stationed in a major army base located in Kumamoto Prefecture, on Japan's southern island Kyushu. Yuichi Sakamoto, the division commander of Japan's main island Kyushu, is one of the 10 members on its crew.
The army reported that the helicopter underwent a routine inspection of safety in late March.