“South Korea’s military has expressed concern at intelligence reports that indicate that more than 50 North Korean submarines have sortied from their bases. The sheer number of vessels that have put to sea means it is impossible to track all of the submarines, officials said, even though the boats are largely outdated and technically obsolescent versions produced in the 1960s for the Soviet Union. Nevertheless, by swamping the South’s maritime defences, the North’s submarines may be able to land infiltration parties on the coast to carry out attacks behind the front line. Alternatively, they may target warships of the South Korean or US navies.”
http://www.thestarphoenix.com/business/More+than+North+Korean+subs+missing+from+their+bases+talks/11313070/story.html
