Why did South Korea fire first? Previous S. Korean governments fully accepted NK's claim to the same territory shelled by the South for no apparent reason on November 23rd.
In fact, this is cold war baloney warmed over. The west used to do similar things to the Sovs in attempting to provoke the Soviet military responses.
South Koreans like playing war games apparently. And guess who taught them. Three guesses - first two don't count, and trust your intuition. HINT: The country in question has 30,000 troops stationed on the peninsula and apparently can't find their way home thousands of miles away.