MELBOURNE, Australia — Japanese fighter jets intercepted Chinese anti-submarine aircraft over the East China Sea last week, marking the first known occasion that this type of Chinese aircraft has been encountered.

In an announcement on March 23, the Joint Staff of Japan’s Defense Ministry announced that its fighter jets had scrambled to intercept a pair of Chinese “Y-9 patrol aircraft. A photo of the Chinese aircraft released by the ministry shows it was a Shaanxi KQ-200 anti-submarine/maritime patrol aircraft with its distinctive magnetic anomaly detector boom used for detecting submarines. The MAD boom is mounted in the aircraft’s rear fuselage and is plainly visible.

A map released by the ministry indicated that the Chinese aircraft flew about 200 miles west of the Japanese island of Okinawa and north of the disputed Senkaku Islands.

The serial number painted on the aircraft’s vertical tail indicates it belongs to the 1st Naval Air Division of the People’s Liberation Army Navy. The division, part of the PLAN’s East Sea Fleet, reportedly received its first KQ-200 in 2018, and the craft is said to be based out of Dachang airbase located in the metropolis of Shanghai.

A satellite photo from April 2018 shows two KQ-200s, with their distinctive MAD booms visible, parked at the base. The flight route of the intercepted aircraft provided by the Japanese Defense Ministry shows the aircraft coming from and returning in the general direction of Shanghai.

The KQ-200, which is also known as the Y-8Q, is one of several variants of special-mission aircraft used by China’s military. It is based on the Shaanxi Y-8 and Y-9 turboprop-powered airlifters. Those Y-8 and Y-9 aircraft come with airborne early warning, electronic warfare, and a variety of electronic and signals intelligence gathering platforms.

In addition to its MAD “stinger,” the KQ-200 is fitted with a chin-mounted surface search radar, an internal weapons bay in the forward fuselage and a comprehensive communications suite.

The first prototype KQ-200s were produced at a Shannxi factory in 2011. Following a development and testing program, the first production aircraft was sighted in PLAN markings and serial numbers as early as 2015, although it was only in May 2017 that the type was reported to be based on China’s southern Hainan island, assigned to the PLAN’s South Sea Fleet.

The PLAN’s North Sea Fleet also recently received the KQ-200. A satellite photo of the air base at Tuchengzi in Liaoning province taken in early February 2019 shows six KQ-200s on the ground.

Japan routinely scrambles its fighter jets to intercept and escort foreign military aircraft operating in its air defense identification zone, even if such aircraft do not approach Japanese airspace. There has been a steady increase of the interception of Chinese military aircraft over the past few years.

Mike Yeo is the Asia correspondent for Defense News.

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