According to the Japan Broadcasting Corporation (HNK), the UH-1 helicopter belongs to US Marine Corps Air Station Futenma in Okinawa prefecture.
The aircraft – together with an AH-1 attack chopper, which was flying with the UH-1 helicopter – landed at the Kumamoto Airport at around 1:20 p.m. local time (04:20 GMT), the media outlet said, citing the Japanese Defense Ministry. Both aircraft landed safely.
The emergency landing was caused by a malfunction of an engine cooling system. The UH-1 was transferred to a Japanese Ground Self-Defense Force camp next to the airport and underwent an inspection, the media outlet added.
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The incident did not affect civilian air traffic, according to the Japanese transport authorities.
The number of incidents involving US military personnel and equipment in Japan has recently increased, fueling the public's opposition to US military bases in the country.