A foreign submarine, believed to be from China, was discovered near Amami Oshima Island, Japan on Jun. 18.
This prompted Japan to dispatch JS Kaga, a helicopter destroyer carrying anti-submarine warfare helicopters and P-1 aircraft to the area to monitor the underwater vessel.
The submarine was observed west of Yokoate Island on Jun. 20 and it passed through a narrow strip of waters between Tokara island chain and Amami Oshima.
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