South Korea, the United States and Japan staged a trilateral maritime interdiction exercise in waters south of the Korean Peninsula this week for the first time in seven years, the South Korean Navy said Tuesday, amid efforts to strengthen security coordination against North Korean threats.

The two-day exercise, which began Monday in international waters southeast of the southern resort island of Jeju along with anti-piracy drills, came after the three countries' defense chiefs agreed to resume the trilateral exercises during their meeting in Singapore in June.

The three sides last staged a maritime interdiction exercise, which focuses on intercepting suspected smuggling vessels, in 2016 and an anti-piracy exercise in 2017.

The latest drills mobilized the South's ROKS Yulgok Yi I Aegis-equipped destroyer, the USS Ronald Reagan aircraft carrier, the Aegis-equipped USS Shoup destroyer, and Japan's JS Hyuga helicopter destroyer among other warships, according to the South's Navy.

"The exercise enhanced the South Korea-US-Japan capabilities in deterrence and response against North Korea's recently advancing nuclear and missile threats, and focused on improving trilateral maritime operational capabilities to respond to maritime security threats and establish a rules-based international order," the Navy said in a release.

Prior to the drills, the three countries held talks between their senior naval commanders on the US aircraft carrier on Sunday to strengthen ways for trilateral response against North Korean threats and for maritime security cooperation.

The meeting was attended by South Korea's Fleet Commander Vice Adm. Kim Myung-soo, US Seventh Fleet Commander Vice Adm. Karl Thomas and Japan's Self-Defense Fleet Commander Vice Adm. Akira Saito.

It also discussed follow-up measures for plans to operationalize a system to share North Korean missile warning data in real-time by the end of this year as reaffirmed by their leaders during their summit in Camp David in August.

"By strengthening maritime-based trilateral training, we will strongly deter and respond against North Korea's nuclear and missile threats," Kim was quoted as saying.

Last month, North Korea unveiled a new "tactical nuclear attack" submarine, with initial state media photos suggesting that it can likely fire submarine-launched ballistic missiles. (Yonhap)