TOKYO (Reuters) -Japan and the United States are conducting a joint military drill involving U.S. aircraft carrier Ronald Reagan in areas around Japan in light of North Korea’s continued missile launches, Japan’s Defense Ministry said on Saturday. North Korea fired two short-range ballistic missiles into the sea on Thursday in the direction of Japan. The missile launch was the sixth in 12 days and the first since Pyongyang fired an intermediate-range missile over Japan on Tuesday. “Amid an increasingly severe security environment surrounding Japan, including North Korea’s repeated ballistic mi…