The powerful weapons found aboard the mystery ship that sank in the East China Sea in December after a shootout with the Japan Coast Guard suggest that the authorities charged with policing and defending the nation's waters face a new challenge.
In an undersea probe in May of the suspected North Korean spy ship, the JCG found that the vessel carried shoulder-fired surface-to-air missiles, a heavy machinegun, automatic rifles and a portable rocket launcher, government sources recently revealed.
The SAMs use an infrared sensor that traces heat emitted by aircraft engines. Vessels intruding into Japan's territorial waters and exclusive economic zone armed with these weapons pose a threat to Maritime Self-Defense Force P3-C patrol aircraft, according to the sources.