South Korean and U.S. troops launched their annual joint drills on Friday, military officials said, amid heightened tension following North Korea’s third nuclear test last month. The Key Resolve/Foal Eagle exercises come after North Korea warned the top U.S. commander in South Korea of “miserable destruction” if the American military goes ahead with the two-month-long joint drills, reported the South Korean /Yonhap/ news agency today. Earlier in the day, the allies started the Foal Eagle drills, which are field training exercises involving tens of thousands of troops from their ground, naval and air forces, a Seoul military official said. They will last until April 30. Separately, South Korean and U.S. troops will conduct computer-simulated drills named Key Resolve from March 11-21. “To join the Foal Eagle drills, U.S. forces from the mainland, the Pacific region and Japan started moving to South Korea,” the military official said on the condition of anonymity. About 10,000 U.S. troops and 200,000 South Korean troops, including reservists, joined the Foal Eagle, according to the official. South Korean and U.S. marines are scheduled to stage a large-scale landing drill and military logistics trainings in case of an emergency on the Korean Peninsula. The Key Resolve drill will involve about 3,500 U.S. troops and 10,000 South Korean troops, the official said.