YOKOSUKA, Japan –
The Los Angeles-class fast-attack submarine USS Santa Fe (SSN 763) and a Japan Maritime Self-Defense Force (JMSDF) submarine conducted Submarine Exercise 25-1 (SUBEX) in the Pacific Ocean, July 12, 2025.
This bilateral exercise portrayed the interoperability and cooperation between the U.S. Navy and JMSDF, showcasing Santa Fe and the JMSDF submarine’s capability to work together while underway in the Indo-Pacific.
“We enjoy a strong bond with our dear partners and friends in the Japanese Submarine Force," said Rear Adm. Lincoln Reifsteck, commander, Submarine Group 7 (CSG 7). "This submarine exercise is just one of dozens of operations our combined forces are planning or executing day in and day out. We take every opportunity to enhance the integration of our undersea forces, reaffirming our commitment to a shared vision of peace and prosperity for our allies and partners in the Indo-Pacific region.”
SUBEX 25-1 was a two-day exercise conducted in the vicinity of Yokosuka between the U.S. Navy and JMSDF, in order to make significant advancements in the joint submarine capabilities and operations. Exercises like this bolster the U.S. and JMSDF momentum in critical undersea warfare and mutual defense.
Both submarine forces continue to work together and progress every day to seamlessly interoperate with each other. This dedication to mutual understanding and shared values of peace and security in the Indo-Pacific reflects the steadfast bonds between the two silent services.
Santa Fe, homeported in San Diego, California, and assigned to Submarine Squadron 11, is conducting routine operations in the U.S. 7th Fleet area of operations.
CSG 7 directs forward-deployed, combat capable forces across the full spectrum of undersea warfare throughout the Western Pacific, Indian Ocean, and Arabian Sea.
U.S. 7th Fleet is the U.S. Navy's largest forward-deployed numbered fleet, and routinely interacts and operates with allies and partners in preserving a secure and prosperous Indo-Pacific region.
For more news from Commander, Submarine Group 7, visit www.csp.navy.mil/csg7/