The childish game of 'chicken' was started by the North. South Korea had no choice but to respond in kind.
This next link (wikimedia) shows the playing field for the war games of South Korea and the U.S. aircraft carrier scheduled for Sunday (good weather or rough seas?). China has warned the U.S. not to enter the Yellow Sea. It's going to be a very active area this month no matter what....
If someone has Google Earth, they will probably see explosions on Sunday unless the military blocks it out.
On Obama's recent trip abroad, did Obama take all of those ships and planes because the U.S. was planning on a big conflict? Where are those ships and planes now?