By Jihoon Lee SEOUL (Reuters) – North Korea fired a ballistic missile towards the sea off its east coast on Sunday, ahead of planned military drills by South Korean and U.S. forces involving an aircraft carrier and a visit to the region by U.S. Vice President Kamala Harris. South Korea’s military said it was a single, short-range ballistic missile fired from near the Taechon area of North Pyongyan Province just before 7 a.m. Japan’s Defence Minister Yasukazu Hamada said Japan estimated it reached maximum altitude at 50 km and may have flown on an irregular trajectory. Hamada said it fell outsi…