During the ongoing multinational Valiant Shield exercise in the Western Pacific, a torpedo fired by a Japan Maritime Self-Defense Force submarine sank the U.S. Navy’s decommissioned amphibious transport dock USS Juneau (LPD-10).

The live-fire sinking—part of the exercise’s SINKEX component—sent the ship to the ocean floor more than 200 nautical miles off the coast in the Mariana Islands Range Complex. Valiant Shield runs from June 22 to July 1, bringing together U.S. and partner forces to train in joint, multi-domain operations across sea, air, land, space, and cyber.

The report notes the USS Juneau sinking is separate from the historic 1942 loss of the earlier USS Juneau (CL-52), which was sunk by a Japanese torpedo during the Guadalcanal campaign. The modern SINKEX similarly used a torpedo from a Japanese submarine, with Navy commanders describing the event as valuable for integrating capabilities and honing coordination needed for high-end maritime operations.