On November 23, 2010 North Korea fired artillery at the South Korean island of Yeonpyeong. This unprovoked attack resulted in the dead of two marines and two civilians with many more injured. South Korea responded by firing back on the N. Koreans. The attacks raised tension between South and North Korea with South Korea saying that it would respond with much more force if attacked again.
I think that South Korea is being a pansy. A better solution would have been to decimate every artillery station that hit them down to the last man and threaten a full scale invasion if the North tried to pull that shit again. Sadly though, I am not in charge of S. Korea's military policy, otherwise this would have never happened.