Unfortunately our fellow hobbyist in left credited by first name alone. Well done Tim Mystery-Call-Sign:
MID-WEST, UNITED STATES — Within hours of South Korean news sources breaking a story that several Sang-Ho class submarines had disappeared from their North Korean bases, a ham radio operator named Tim, picked up a “numbers station” broadcasting on the same frequency as “The Voice of Korea” propaganda station. What makes this even more interesting is that at the tail end of the numbers transmission there was a long duration digital transmission as well.
You can read more about Numbers Stations at: http://www.groundzeromedia.org/communumbers/