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On Monday, North Korea and South Korea exchanged live fire, shelling each other's waters in the Yellow Sea. No fatalities have been reported, and it appears North Korea was only really aiming for provocation, but the trading of potentially lethal artillery is always worrisome when you have hundreds of thousands of troops perpetually ready to resume a Korean War uneasily suspended in armistice since 1954.
North Korea fired first, sending at least one shell south of the disputed maritime border, called the Northern Limit Line, a little after noon and sending residents of South Korea's Baengnyeong and Yeonpyeong islands into shelters. Conflicts along the NLL aren't all that uncommon, but there was an odd twist to this exchange of live artillery: This time, North Korea warned Seoul beforehand.
At about 8 a.m., Pyongyang sent South Korea's Second Fleet headquarters a fax saying that it would perform live-fire drills later that day at seven points on the North Korean side of the NLL, and warning the South to move its vessels out of the area. North Korea is upset that the U.S. and South Korea are conducting annual military exercises, as it is each year, and it's threatening "a new form of a nuclear test aimed at strengthening our nuclear deterrence." --Peter Weber