U.S. and UK Sink Former Frigate to Validate Joint Maritime Strike in Atlantic Thunder Exercise.

USS Paul Ignatius fired an anti-surface SM-6; HMS Portland launched a Naval Strike Missile, a Wildcat helicopter employed Sea Venom, and USS Massachusetts delivered the final strike with an Mk 48 ADCAP torpedo. The coordinated engagement demonstrated how U.S. and UK forces can combine multiple sensors and weapon systems across surface, air and subsurface domains during a single maritime attack.

USS Paul Ignatius opened the engagement with the anti-surface variant of the SM-6, while HMS Portland fired a Naval Strike Missile and a Wildcat helicopter from 815 Naval Air Squadron launched Sea Venom before USS Massachusetts delivered the final strike with an Mk 48 ADCAP heavyweight torpedo. Conducted at the UK Ministry of Defence Hebrides Range, the sequence linked U.S. and British sensors, targeting procedures and launch platforms across the surface, air and subsurface domains, providing a live-fire test of how both navies could coordinate a distributed maritime strike against a hostile surface combatant.

Related News: US and UK Navies to sink Cold War frigate USS Klakring in Atlantic Thunder 26 joint live-fire exercise

HMS Portland launches a Naval Strike Missile during Exercise Atlantic Thunder 2026, while USS Paul Ignatius fires an SM-6 during the same live-fire sinking exercise in the North Atlantic. (Picture source: Royal Navy/U.S. Navy)

The destruction of a 43-year-old Oliver Hazard Perry-class frigate was less important than the attack chain used against it. USS Paul Ignatius, an Arleigh Burke-class destroyer, fired an anti-surface variant of the Standard Missile 6, while HMS Portland engaged the target with a Naval Strike Missile. A Wildcat from 815 Naval Air Squadron then launched a Sea Venom before the Virginia-class attack submarine USS Massachusetts finished the ship with an Mk 48 Advanced Capability torpedo. U.S. and British P-8 aircraft also took part in the exercise, expanding the detection and targeting architecture around the surface target.

The U.S. Navy said Atlantic Thunder concluded on September 25 after training joint targeting procedures, tactics and live firing against a vessel at sea. U.S. units assigned to Task Forces 65, 67, 68, 69 and 1060 participated alongside British forces. Before the attack, teams from Naval Surface Warfare Center Carderock and Naval Information Warfare Center Pacific installed sensors aboard Klakring to record damage and system failures caused by each impact. This instrumentation turned the SINKEX into a weapons-effects assessment campaign, allowing engineers to compare the damage produced by several types of munitions against the same hull.

The U.S. missile firing is notable because the SM-6 is no longer limited to air and missile defense missions. The U.S. Navy has already validated its use against surface vessels, supported by a guidance architecture combining active and semi-active radar homing. During Atlantic Thunder 26, Paul Ignatius was credited with demonstrating the range and effects of the anti-surface variant, although the exact engagement distance was not disclosed. The destroyer can therefore engage distant naval targets without requiring changes to its launch architecture, as the SM-6 is fired from the Mk 41 Vertical Launching System.

For the Royal Navy, the firing from HMS Portland reflects a separate capability transition. The Naval Strike Missile is a sea-skimming anti-ship weapon capable of striking targets at more than 100 miles, or over 160 kilometers, while traveling at close to Mach 1. It is replacing Harpoon aboard selected British warships pending the introduction of the Future Cruise Anti-Ship Weapon. Sea Venom provides an additional shorter-range layer from the air. The Royal Navy states that a Wildcat can carry four missiles and that the weapon is intended to destroy corvette-sized vessels or disable larger frigates and destroyers. Atlantic Thunder marked the first live firing of an operational Sea Venom from a Wildcat against a representative maritime target.

The final strike came from below the surface. USS Massachusetts fired an Mk 48 ADCAP, a heavyweight torpedo used by U.S. submarines for anti-submarine and anti-surface warfare. The weapon has a diameter of 533 mm, weighs about 1,700 kg, and carries a warhead of roughly 295 kg. Its acoustic homing system and digital guidance architecture allow software updates to be integrated over time, adapting the torpedo to changing targets and countermeasures.

From an operational perspective, Atlantic Thunder primarily shows how a naval attack can be distributed across several launch platforms rather than depend on one ship and a single family of weapons. A long-range missile fired from an Aegis destroyer, a sea-skimming anti-ship missile launched by a frigate, a precision weapon released from a helicopter, and a torpedo fired by a submarine create different approach axes, signatures, and defensive requirements for the same target. P-8 aircraft and other participating assets help build and maintain the tactical picture, while instrumentation aboard the target vessel measures the effects of each hit. For commanders, the central issue is therefore the connection between detection, identification, weapon assignment and battle-damage assessment across several domains and two armed forces.

Atlantic Thunder 26 also takes place as European navies deepen cooperation in the North Atlantic, Baltic Sea and High North. On the same day the firing results were released, the Royal Navy highlighted closer naval cooperation within the Joint Expeditionary Force, including training, logistics and capability development. The sinking of Klakring provides a practical example of that approach. U.S. and British forces are not only operating alongside one another but rehearsing how sensors, surface ships, aircraft, submarines and new anti-ship weapons can be integrated into a single strike chain. In a region where NATO relies on secure sea lines to move forces and reinforcements quickly, this ability to coordinate attacks across several domains is directly linked to control of maritime approaches and the capacity to engage hostile naval forces at range.

Written By Erwan Halna du Fretay - Defense Analyst, Army Recognition Group
Erwan Halna du Fretay holds a Master’s degree in International Relations and has experience studying conflicts and global arms transfers. His research interests include security and strategic studies, particularly the dynamics of the defense industry, the evolution of military technologies, and the strategic transformation of armed forces.