South Korea, the US and Japan on Monday began an anti-submarine exercise designed to counter North Korea’s growing threats from submarine-based ballistic missiles, South Korea’s Navy said.

The three-day exercise took place in waters between South Korea and Japan, near Jeju Island, where the three countries’ navies searched for and tracked a mock submarine, protected high-value units under a contingency scenario, and carried out anti-submarine defense maneuvers.

Joining the drill are South Korea’s 4,500-ton Kang Gam Chan destroyer and a Lynx helicopter; US Aegis Destroyer USS McCampbell, a MH-60 anti-submarine chopper, and a P-3 Orion patrol plane; and Japan’s Sawagiri destroyer and an anti-submarine chopper.

“The drill was intended to improve the three countries’ anti-submarine search, identification and tracking capabilities so as to ensure their effective response to threats from North Korea, which is developing SLBMs,” the Navy said in a statement.

The US Navy’s 7th Fleet based in Japan said in a separate statement that the drill will promote communications, interoperability and partnership between the three navies. “The training will allow participants to enhance tactical maritime capabilities, strengthen cooperation and improve shared situational awareness.”

Seoul’s Defense Ministry spokesman Moon Sang-gyun said the three countries agreed to hold the exercise during the Defense Trilateral Talks in December, refuting a Japanese news report that Seoul had rejected an earlier proposal following the signing of its intelligence-sharing deal with Tokyo last November.

Pyongyang has been spurring its SLBM development in recent years, especially since its launch of a submarine capable of firing ballistic missiles and an ejection test in 2015. Last August, leader Kim Jong-un hailed another SLBM test as the “greatest success,” and the country unveiled a new intermediate-range missile in February built on its SLBM technology.

By Yeo Jun-suk (jasonyeo@heraldcorp.com)