N.Korea vows to strike back if South holds island drill 16 Dec 2010 North Korea's military threatened Friday to strike back with deadly firepower if South Korea goes ahead with a live-fire drill on the border island of Yeonpyeong. The North "will deal the second and third unpredictable self-defensive blow" to protect its territorial waters if the South holds the one-day drill scheduled sometime between Saturday and Tuesday, it said.