Nimitz Carrier Strike Group conducts drills with South Korea & Japan.

According to information published by the US DoD on April 4, 2023, the Nimitz Carrier Strike Group (NIMCSG) conducted a trilateral maritime exercise with the Japan Maritime Self-Defense Force (JMSDF) and the Republic of Korea Navy (ROKN).
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Chungmugong Yi Sun-Shin-class destroyers ROKS Dae Jo young and ROKS Choi Young, and So Yang-class fast combat support ship ROKS So Yang steam in formation with the aircraft carrier USS Nimitz. (Picture source: US DoD)

Participants included the aircraft carrier USS Nimitz (CVN 68), the Arleigh Burke-class guided-missile destroyers USS Decatur (DDG 73) and USS Wayne E. Meyer (DDG 108), JS Umigiri (DD 158) of the JMSDF, and ROKS Yul Gok Yi (DDH 992), ROKS Dae Jo Young (DDH 977), ROKS Choi Young (DDH 981), and ROKS So Yang (AOE 51) of the ROKN.

NIMCSG has conducted bilateral exercises with the JMSDF and ROKN on separate occasions during its current deployment prior to the three countries integrating for this exercise. Combined operations included anti-submarine exercises, search and rescue exercises, and staff embarkations.

The U.S. Navy has a strong presence in the region with its Seventh Fleet, which is the largest forward-deployed numbered fleet. The fleet regularly interacts and operates with allies and partners.

Japan and US have a Mutual Defense Treaty that obligates each other to cooperate in maintaining regional security and stability. The U.S. Navy and Japan Maritime Self-Defense Force regularly conduct joint exercises, which contribute to strengthening interoperability and enhancing the capabilities of both navies.

Similarly, the United States and South Korea have a strong military alliance. The U.S. military has a significant presence in South Korea, with over 28,500 troops stationed in the country. The U.S. and South Korean navies conduct joint exercises, which help improve their abilities to deter and defend against potential security threats.

Trilateral naval cooperation between the U.S., Japan, and South Korea has also been increasing in recent years. Their maritime security cooperation has intensified with the increasing threats in Northeast Asia, including North Korea's ballistic and nuclear missile programs.