The UK Test-Fires U.S. Torpedo Using Uncrewed Undersea Vessel

U.K.’s Major Step in Maritime Defense

The United Kingdom has test-fired a U.S. torpedo from an uncrewed undersea vessel for the first time. This action is regarded as a significant advancement for Euro-Atlantic security and NATO’s naval capabilities.

General Sir Gwyn Jenkins, the U.K.’s First Sea Lord, recently stated that the nation requires more warships and drones to secure the Atlantic. He highlighted Russia as the largest threat, emphasizing its advanced submarines and sophisticated underwater systems.

On Monday, Britain’s Ministry of Defence (MOD) revealed that the U.K. had fired a heavyweight torpedo from the 40-foot-long undersea drone XV Excalibur. This marked the first such launch by either the U.K. or U.S. from an uncrewed undersea vessel. MOD noted the technological collaboration between the U.S., U.K., and Australia under the AUKUS alliance.

“AUKUS is producing a new fleet of innovative attack submarines and undersea autonomous capabilities to deter adversaries long into the future,” the MOD stated.

Details on XV Excalibur

Although the MOD statement did not mention the trial’s location or date, U.K. Minister of State for Defence Luke Pollard cited a testing range off Scotland’s north coast. Navy Lookout reported sightings of XV Excalibur at Kyle of Lochalsh, hinting the trial may have occurred at the British Underwater Test and Evaluation Centre (BUTEC).

Pollard described this development as key to building a hybrid navy, combining crewed with uncrewed vessels, ensuring security in the North Atlantic especially against hostile nations like Russia.

Excalibur is classified as an Extra-Large Uncrewed Underwater Vehicle (XLUUV), built by Plymouth-based MSubs and developed as part of the Royal Navy’s Project Cetus. As a 12-meter vessel displacing 19 tonnes, it is the largest uncrewed underwater craft trialed by the Royal Navy.

Excalibur underwent extensive three-year development, unveiled in May 2025 at Devonport, leading to two years of sea trials. In 2025, the U.K. and Australia tested Excalibur during Exercise Talisman Sabre, demonstrating remote control capability from an Australian center.

Although Excalibur has no torpedo tubes, it features a large central payload bay. The 5.8-meter Mk 48 torpedo likely released from a cradle attached to the hull during trials, due to size constraints.

“Firing torpedoes from uncrewed systems and Astute-class subs represents a substantial increase in our lethality,” Pollard added.

Understanding AUKUS

The Excalibur trial marks a significant breakthrough in Euro-Atlantic security and NATO’s undersea capabilities, as emphasized by MOD. AUKUS, the defense partnership involving Australia, the U.K., and the U.S., was initially announced on 15 September 2021 to address China’s perceived threat.

AUKUS comprises Pillar 1, focused on Australia acquiring nuclear-powered attack submarines and rotating allied submarines through Australian waters. Pillar 2 fosters collaboration in undersea tech, AI, and electronic warfare domains.

On May 30, the AUKUS partners unveiled the first Pillar II signature project, aiming to develop payloads and systems for uncrewed undersea vehicles (UUVs).