US, South Korea, Japan to begin joint anti-submarine drills on Sep 30

South Korea, the United States and Japan will hold trilateral anti-submarine drills in the international waters of the East Sea later this week for the first time in more than five years.

The three countries are set to stage the training on September 30, as Pyongyang has been pushing to develop submarine-launched ballistic missiles (SLBMs) while codifying an assertive nuclear policy that leaves open the possibility of preemptive strikes in a contingency, Seoul officials said on September 29, amid evolving North Korean military threats.

The countries last held such trilateral maritime drills in April 2017, according to Yonhap News Agency.

For this year's edition, they mobilized an array of warships, including South Korea's Munmu the Great destroyer; the USS Ronald Reagan aircraft carrier and members of its strike group; and Japan's Asahi-class destroyer.

"The training is part of the defence ministry's steps to restore military cooperation among South Korea, the US and Japan to a level before 2017, so as to respond to North Korea's nuclear and missile threats," the ministry said in a statement sent to reporters.

The training will focus on detecting, identifying and tracking North Korean submarines equipped with capabilities to launch SLBMs.

"We have chosen the international waters of the East Sea as the training area in consideration of North Korea's SLBM threats and key areas of submarine activities," the ministry said.

In a separate release, the US military said three-way operations "concretely demonstrate our shared, unwavering commitment to upholding regional security and stability."

"Exercises, such as this, forge a trilateral relationship between Japan, Republic of Korea and the United States that is forward-leaning, reflective of our shared values, and resolute against those who challenge regional stability," reads a statement posted on the US 7th Fleet's website.

It added, "This exercise will promote interoperability, tactical and technical coordination, and efficient communications between the three countries."

Meanwhile, Seoul's defence ministry said it is "very regrettable" that the plan for the training, which requires a "considerable level of security," had been leaked in advance of an announcement through a private social media account, in a reference to the disclosure by Rep. Ahn Gyu-back of the main opposition Democratic Party.

The previous day, Ahn wrote on his Facebook account that the drills are set to take place just around 150 kilometres away from South Korea's easternmost islets of Dokdo, over which Japan has persistently claimed sovereignty.