As the United States and South Korea begin joint naval exercises residents of a South Korean border island shelled by North Korea last week have been briefly ordered to take shelter in bunkers. North Korea has warned that it will carry out attacks if the US-South Korean exercises west of the Korean peninsula violated territorial waters. People living on Yeonpyeong, the island that was attacked by North Korea were told to take shelter after one artillery round was heard from North Korean territory just a few kilometers away. The order was lifted 40 minutes later. That frontline area is tense as the joint military drills gave underway further south in the Yellow Sea. South Korean media is reporting that the North has move surface to air and surface to surface missiles closer to its border with the South