The U.S. Navy's Sixth Fleet and the UK Royal Navy have completed two weeks of joint military training under Exercise Atlantic Thunder 26, culminating in a live-fire SINKEX off the coast of Scotland.
The exercise ran from September 14 through September 25 and brought together U.S. and British naval and air assets for multi-domain training focused on long-range maritime operations, weapons systems, targeting networks and information sharing.
U.S. European Command said the exercise concluded with the sinking of the decommissioned frigate USS *Klakring* during a series of coordinated air and surface strikes.
The exercise had originally been scheduled for May but was postponed until September. Preparatory activities began with a pre-sail conference at Faslane, Scotland, on September 10.
According to U.S. commanders, Atlantic Thunder 26 was designed to strengthen interoperability between the two navies and improve their ability to operate together across multiple domains.
U.S. Navy forces participating in the exercise included the Arleigh Burke-class guided-missile destroyer USS *Paul Ignatius* and the submarine USS *Massachusetts*. The Royal Navy contributed HMS *Portland*, while aircraft from the Royal Air Force and U.S. Air Force also took part.
The exercise also included planned trials involving Royal Navy unmanned underwater vehicles. The systems were intended to support underwater operations and provide additional information following the live-fire phase.
### SINKEX Sends USS *Klakring* to the Seabed
The final phase involved USS *Klakring*, a former U.S. Navy frigate that had been decommissioned in 2013.
The 4,100-ton vessel was built by Bath Iron Works and commissioned in 1983. Measuring 453 feet (138 meters), the frigate served for decades before being laid up in Philadelphia. It was later towed to Scotland for use as the exercise target.
The SINKEX was conducted in the Hebrides Range, approximately 150 nautical miles offshore. U.S. European Command said coordinated air and surface strikes eventually sent the former frigate to the seabed at a depth of approximately 6,000 feet.
Following the sinking, uncrewed underwater vehicles were expected to survey the seabed and examine the condition of the target and surrounding area.
Atlantic Thunder 26 marked the first time in four years that the U.S. and UK navies have conducted joint training featuring a SINKEX. During a similar exercise in 2022, the two navies sank the former USS *Boone*, an Oliver Hazard Perry-class frigate.
U.S. European Command has indicated that additional information about Atlantic Thunder 26 and the results of the exercise will be released later.
The exercise forms part of ongoing U.S.-UK naval cooperation, with both countries continuing to conduct combined training designed to improve operational coordination, information sharing and interoperability.