Explanation:

 The        250         km          wide      passageway Miyako Strait between the Miyako and Okinawa islands is seen as a major choke-point through which China‘s People‘s Liberation Army Navy can channel into the West Pacific, dominated by the U.S. Navy.

•              Recently, large ships of the Japanese Coast Guard keep a tight round- the-clock vigil on this group of Islands.

•              Their mission is to ensure that Japan maintains its hold over these small but strategically significant islands in the East China Sea.