South Korea and the U.S. held a joint live-fire air drill on the Yellow Sea this week.

South Korea’s air force said Friday that it held air-to-air and air-to-surface bombing drills at a maritime shooting range with the U.S. 51st fighter wing from Monday to Friday.

They were part of the Warrior Shield field training maneuvers in connection to the Freedom Shield joint exercise.

The air drill mobilized South Korean fighter jets including the F-35A as well as the A-10 Thunderbolt from the U.S. 

South Korean air force said the drill focused on verifying precision strike capabilities and performance of the preemptive strike strategy known as the “Kill Chain."