"i wonder what they're fishing for?"
It appears they are playing peek a boo with the boundary water just to gauge Japan's reaction.
I think they are testing the waters as distraction and reconnaissance in preparation for some planned advance (NK?) or perhaps responding to an unpublished incident closer to their shoreline.
Dutch Soldiers Lay Siege to House After Officers Hurt (Update1)
Nov. 10 (Bloomberg) -- Dutch military special forces laid siege to a house in The Hague after three police officers were injured in a hand-grenade blast during an anti-terrorist raid. Authorities closed the airspace over the city to civilian flights.......
http://quote.bloomberg.com/apps/news?pid=10000087&sid=aWLFKl7Ew.Rw&refer=home
Rumors, vile rumors....