South Korea’s navy and marine corps on Monday carried out the “decisive action” phase of a large-scale biennial amphibious landing drill on the eastern coast in an exercise that accounts for potential military threats from North Korea.

The eight-day, brigade-level exercise ending April 30 in the southeastern city of Pohang involves around 3,200 troops from the army, navy, air force and marine corps, the ROK navy said in a press release Monday.

Monday’s “decisive action” (결정적 행동) centerpiece took place at Dokseok-ri Beach, where marines — backed by simulated naval gunfire and air support — moved to secure a beachhead