South Korea and the U.S. held antisubmarine attack drills on Tuesday morning, the third day of joint maritime exercises in the East Sea.

The Combined Forces Command and the Joint Chiefs of Staff in Seoul say the drills in waters just east of Gangwon Province comprised of underwater infiltrations and simulated attacks on enemy subs.

Antiaircraft and antiship drills also took place, as well as live-fire drills against submarines and exercises using depth charges.

A special warfare unit simulated detecting and attacking North Korean forces attempting to infiltrate via the sea.

F-15K and F-16 fighter jets flew from the East Sea to areas over the Gangwon and Gyeonggi provinces as part of air-to-surface maneuvers.

The North Korean Navy is believed to own 260 troop transport vessels including 130 hovercrafts and 90 high-speed landing crafts.