The decommissioned US Navy frigate, ex-USS Klakring (FFG 42), was sunk in the North Atlantic during Exercise Atlantic Thunder 2026, a US-UK multi-domain sinking exercise led by the US 6th Fleet.
The Oliver Hazard Perry-class guided-missile frigate was used as the surface target during the exercise, which concluded on September 25. US and UK forces conducted live-fire engagements against the ship to train in maritime strike, targeting and battle damage assessment.
The US Navy guided-missile destroyer USS Paul Ignatius (DDG 117) employed an anti-surface variant of the Standard Missile-6 (SM-6), while the Virginia-class attack submarine USS Massachusetts (SSN 798) engaged the target with a Mk 48 Advanced Capability torpedo. The torpedo strike resulted in the final hit that sank ex-USS Klakring.
Royal Navy frigate HMS Portland (F 79) also participated in the exercise, with the Royal Navy confirming the firing of the Naval Strike Missile (NSM) and Sea Venom. US Navy and Royal Air Force P-8 maritime patrol aircraft, a Royal Navy Wildcat helicopter and US Air Force F-15E Strike Eagles also took part.
“The successful firing of NSM marks a significant milestone for the Royal Navy, demonstrating our ability to deliver credible, modern maritime strike capability,” said Royal Navy Lt. Cmdr. Louise Kirkaldy, HMS Portland’s Principal Warfare.
“This achievement reflects the professionalism, dedication and teamwork of all those involved, whose hard work has ensured we remain ready to meet the challenges of today and tomorrow.”
Before the SINKEX, Naval Surface Warfare Center Carderock and Naval Information Warfare Center Pacific installed sensors on the target ship to collect data during the engagements.
The information will be used for post-exercise battle damage assessments and to support future analysis of system failures and repair requirements, the officials noted.
Ex-USS Klakring entered US Navy service on August 20, 1983, and was decommissioned on March 22, 2013. The frigate was named after Rear Adm. Thomas B. Klakring, a World War II submarine commander who was awarded three Navy Crosses.
"Atlantic Thunder demonstrates the unmatched lethality and interoperability of the United States and United Kingdom," said US Capt. Kelechi Ndukwe, Commander, US Task Force 65.
"This sinking exercise not only validated the power behind U.S.-UK offensive weapons but delivers a clear message to adversaries that the U.S. Navy and Royal Navy remain a ready allied force."
The US Navy said former warships used as SINKEX targets undergo extensive preparation and cleaning in accordance with environmental regulations before being transported for sinking. During Atlantic Thunder, US and UK personnel also conducted monitoring above and below the surface to reduce risks to the marine environment and marine mammals.
The exercise strengthens the US-UK alliance, warfighting credibility, and interoperability during long-range maritime sinking operations.