South Korea and the United States have completed their combined anti-submarine warfare naval exercise in waters near Guam.

According to the South Korean Navy on Sunday, the naval drill, known as “Silent Shark,” involved the one-thousand-800-ton-class submarine “Jung Ji” and two P-3 maritime surveillance patrol aircraft from the South Korean Navy, as well as one submarine and one aircraft from the U.S. Navy.

During the drill, which was held from October 6 to Sunday, the navies of the two countries conducted “submarine-to-submarine” training, which involves searching, tracking, and attacking each other's submarine as a virtual enemy, and an anti-submarine attack and defense training that involved searching for, destroying and infiltrating enemy submarines.

Kim Il-bae, the commander of the Jeong Ji, said that through fierce and realistic training, the allies increased their ability to carry out joint operations for anti-submarine warfare. He vowed to deter enemy aggression and to firmly defend the country’s seas based on their solid combined defense readiness.

The Silent Shark exercise has been held every other year since 2007 to improve joint operation capabilities and strengthen interoperability between South Korea and U.S. navies in order to counter North Korean submarine threats.