According to this CNN news item

North Korea slams use of its flag in U.S.-South Korean military drills - CNN.com

the US and South Korea flew a North Korean flag to mark an area that was considered to be "enemy" territory during a joint exercise. As usual, the North Koreans are apoplectic. I don't have any sympathy for the obnoxious, tyrannical regime in North Korea, but it seems to me that they have a point here. As the article points out, the two Koreas are still technically at war. Flying an enemy flag in a live fire simulated combat situation 30 miles away from the enemy's border doesn't sound like the wisest thing to do.

Peter Ansoff