The navies of South Korea, the United States and Japan began a joint missile detection exercise Tuesday in a bid to boost trilateral military cooperation in detecting and tracking North Korean missiles.
The ROK Navy said the two-day drill was being held in South Korean and Japanese waters.
The trilateral naval drill is separate from the ongoing joint annual Foal Eagle and Key Resolve exercises by Seoul and Washington, the Navy noted.
The exercise is designed to train sailors to share information on detecting and tracking enemy missiles, the Navy said, adding that the missile interception part was excluded from this drill.
During the simulation exercise, three Aegis-equipped destroyers ― the Sejongdaewang from South Korea, Curtis Wilbur from the U.S. and Kirishima from Japan ― were mobilized.
"The Aegis destroyer from each country detects and tracks a mock hostile missile as if fired by the North, and then exchanges relevant information among them," the Navy said.
"The drill is taking place in accordance with an agreement, made at the Seoul and Washington's Security Consultative Meeting in October 2016."
At last year's SCM, South Korea and the U.S. defense chiefs agreed to hold the trilateral missile warning exercise regularly.
The ongoing drill marks the fourth of its kind since last June, when the three countries held the exercise near Hawaii. Since then, they have held the drills last November and in January this year in the sea between South Korea and Japan.
The drill also marks the second of its kind after South Korea and Japan signed an information-sharing accord, known as the General Security of Military Information Agreement (GSOMIA), last November.
However, the Navy said that the Aegis destroyers of the two countries would not share information directly during the drill, but would do so indirectly through U.S. satellites.
"As the GSOMIA has been signed, South Korea and Japan are making efforts to interlock systems of their Aegis destroyers so that their information-sharing ability can be improved," a Navy official said.
The official added that the trilateral drill was unrelated to the U.S.-led missile defense system (MD), playing down speculation that Seoul could drift into Washington's global missile defense program.
Japan officially announced its participation in the U.S. MD in 2003.
U.S. aircraft carrier arrives Wednesday
Meanwhile, Washington's Nimitz-class aircraft carrier Carl Vinson and its strike group will arrive in Busan, Wednesday, to participate in the Key Resolve and Foal Eagle exercises.
The carrier strike group with 5,500 crew includes the destroyer Wayne E. Meyer and aircraft from Carrier Air Wing 2.
Officials said sending the Carl Vinson Strike Group demonstrated U.S. intent to deter North Korea amid tensions surrounding Pyongyang's evolving missile and nuclear weapons programs.
The reclusive state fired four ballistic missiles on Mar. 6, 22 days after it fired a new intermediate-range ballistic missile.
There has also been speculation that Pyongyang will stage another major provocation such as a sixth nuclear test or launching an intercontinental ballistic missile aimed at the U.S. mainland.