South Korea and the United States began a joint live-fire aerial exercise Monday, the South Korean Air Force said, in the latest move to reinforce capabilities to counter North Korean threats. The three-day exercise got under way earlier in the day over waters off South Korea's western coast, mobilizing some 60 military planes, including South Korea's F-35A, F-15K and KF-16 fighters and U.S. A-10 attack aircraft, according to the Air Force. It said the exercise is designed to inspect response procedures to simultaneous air and land provocations by the North, such as cruise missile launches and long-range artillery firings. During this week's drills, F-35As and F-15Ks will practice firing missiles to neutralize aerial targets, while KF-16s and U.S. A-10 aircraft will drop air-to-ground weapons to destroy simulated origins of provocation by the enemy. On Monday, the F-35As fired AIM-120C medium-range air-to-air missiles, while the KF-16s dropped GBU-31 joint direct attack munitions that can penetrate 1-met er-thick reinforced concrete, the Air Force said. "We will maintain a strong posture to immediately respond to any provocations by the enemy," Maj. Cha Seung-min, a South Korean pilot who participated in the drills, said in a release. The live-fire exercise is taking place in conjunction with the allies' 11-day Ulchi Freedom Shield exercise set to conclude Thursday. North Korea has long denounced joint drills between South Korea and the United States as rehearsals for an invasion against it. Source: Yonhap News Agency