Tensions on the Korean Peninsula are high in the wake of North Korea's underground nuclear test in February. The U.S. military said it was bolstering its missile defense shield on the U.S. West Coast and said it flew stealth bombers over South Korea during military drills.
South Korean Defense Ministry spokesman Kim Min-seok said authorities were having a tough time determining why North Korea activated some of its own missile operations.
"Signals have been on and off, but the situation comes to an end only when (the North) withdraws (its missiles)," he was quoted by the Yonhap news agency as saying. "It is hard to grasp the North's intention whether it is for real or for manipulation."
U.S. and South Korean military forces quietly marked the end to two months worth of joint military drills Tuesday. The North Korean government said it viewed those drills, dubbed Foal Eagle, as preparation for war.
North Korea may be preparing large-scale military exercises along its western coast, Yonhap reports.