The plan will see South Korean military taking the lead in "local" provocations. The top U.S. general on the Korean peninsula would still lead military operations if full-scale war were to break out, Stars and Stripes said Sunday.
The two sides didn't say what would constitute a "local" attack and what would rise to the level of war.
The protocol was developed after the North shelled Yeonpyeong Island in November 2010, killing four South Koreans, including two civilians.
It is widely suspected North Korea may try a similar provocation once an annual training exercise between the U.S. and South Korean militaries concludes this month -- testing newly elected South Korean President Park Geun-hye.