SEOUL, South Korea (AP) – North Korea says leader Kim Jong Un supervised a live-fire demonstration of newly-developed short-range ballistic missiles he said would send an “adequate warning” to the United States and South Korea over their joint military exercises. The announcement by Pyongyang’s official Korean Central News Agency on Wednesday came a day after South Korea’s military said it detected the North firing two projectiles that were likely ballistic missiles into the sea. Tuesday’s launches were the North’s fourth round of weapons tests in less than two weeks. Experts say the country’s testing activity could intensify if progress isn’t made on nuclear negotiations with Washington. KCNA says two missiles launched from a western airfield flew cross-country and over the area surrounding capital Pyongyang before accurately hitting an island target off its eastern coast.