A view of a test launch of a new solid-fuel intercontinental ballistic missile (ICBM) Hwasong-18
A view of a test launch of a new solid-fuel intercontinental ballistic missile (ICBM) Hwasong-18 at an undisclosed location in this still image of a photo used in a video released by North Korea's Korean Central News Agency (KCNA) April 14, 2023. KCNA via REUTERS. Reuters

South Korea, the United States and Japan staged joint naval missile defence exercises on Monday, in a push to improve security co-operation and respond better to North Korea's evolving missile threats, Seoul's navy said.

The news came days after the three nations agreed at talks in Washington to hold regular missile defence and anti-submarine exercises in their efforts to boost diplomatic and military co-operation.

Tension has simmered in recent weeks as the North ramped up military activities, testing a new solid-fuel intercontinental ballistic missile on Friday that experts say would ease the way for missile launches with little warning.

Monday's drills in international waters between Korea and Japan bring together South Korea's 7,600-tonne Aegis destroyer Yulgok Yi I, the U.S. guided-missile destroyer Benfold, and Japan's Atago destroyer, also equipped with Aegis radar systems.

The effort focuses on mastering response procedures, from detection and tracking to information sharing, by creating a virtual target in a scenario featuring a North Korean ballistic missile provocation, the South's navy said.

"It is an opportunity to strengthen trilateral security cooperation against North Korea's escalating nuclear and missile threats," Captain Kim Ki-young of the South Korean destroyer said in a statement.

This would solidify the navy's capability and posture to respond to ballistic missiles, he added.

Pyongyang has threatened "more practical and offensive" action as South Korea and U.S. forces have performed annual springtime exercises since March, some involving Japan, which the North has described as a rehearsal for nuclear war.

Separately, the air forces of South Korea and the United States are set to begin drills on Monday for a 12-day run.

Also on Monday, South Korea and Japan resumed "two-plus-two" talks of senior diplomatic and security officials in Seoul after a five-year halt, as ties thaw after a years-long feud over issues of wartime history.

They shared views on North Korea and regional issues, while agreeing to improve understanding of each other's policies and foster security co-operation in a "forward-looking" way, Seoul's foreign and defence ministries said in a joint statement after the meeting.

President Yoon Suk Yeol, who has pledged to move ties with Japan beyond the past, visited Tokyo in March for the first time in 12 years as South Korea's leader.