The encounter ended in the sinking of the North Korean vessel, which the Japanese authorities later announced was determined to have been a spy craft.

The armed trawler was detected by a communications station in Kikaijima, Kagoshima, which was under control of the Japanese Defense Intelligence Headquarters.

[9] A six-hour firefight ensued, in which over 1,000 machine gun rounds were fired by both sides;[1] the North Korean crew were said to have wielded shoulder-held rocket launchers.

According to The Guardian, "fifteen survivors were seen clinging to a buoy in heavy seas, but the Japanese ships were ordered to ignore them because of fears that they would use force to resist capture".

It was revealed that the vessel was camouflaged as a Chinese or Japanese fishing boat and that it could reach a speed of 33 knots (61 km/h; 38 mph), far faster than any commercial trawler.