South Korean and US military aircraft have staged regular combined live-fire drills to strengthen readiness against North Korean threats, Seoul's Air Force said Tuesday, amid heightened tensions over Pyongyang's failed satellite launch.

More than 90 aircraft, including the South's F-35A stealth fighters and the US A-10 attack aircraft, have been mobilized for the four-day exercise that began Monday over waters off South Korea's west coast, according to the Air Force.

The exercise is focused on strengthening the participating pilots' strike capabilities and bolstering readiness against possible enemy provocations, it said.

This week's drills will take place in the wake of North Korea's botched attempt to launch a military spy satellite into orbit Monday night.

The North's rocket exploded minutes after liftoff from the North's major satellite launch site on the northwestern coast, according to the South's military. (Yonhap)