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By Brendan Cole
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The U.K. has test-fired a U.S. torpedo from an uncrewed undersea vessel for the first time in a move that has been dubbed a major development for Euro-Atlantic security and NATO's naval capabilities.
It follows comments by the U.K.'s First Sea Lord, General Sir Gwyn Jenkins last week that the U.K. needs more warships and drones to protect the Atlantic because "the greatest threat to our security today is Russia."
Jenkins told an event in Whitehall, London, that Russia has advanced submarines that are becoming harder to track and have long-range precision weapons, as well as specialist systems designed to operate deep underwater.
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Britain's Ministry of Defence (MOD) on Monday said the U.K. had fired a heavyweight torpedo from a 40-foot-long undersea drone manufactured in Britain named XV Excalibur.
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The launch was the first time either the U.K. or U.S. had launched a torpedo from an undersea uncrewed vessel. It showed the technological collaboration of the U.S., the U.K. and Australia (AUKUS) alliance the MOD added.
"This is significant—it shows naval drones taking the next step by incorporating lethal strike packages. If fielded in mass, this would threaten China's ability to operate naval forces in the Western Pacific, especially around Taiwan," Mark Cancian, senior adviser at the Center for Strategic and International Studies (CSIS), told Newsweek.
When contacted for comment, the MOD referred Newsweek to its statement that AUKUS is producing a new fleet of innovative attack submarines and undersea autonomous capabilities "to deter adversaries long into the future."
What Do We Know About XV Excalibur?
The MOD statement did not specify a location or a date for the trial but U.K. Minister of State for Defence Luke Pollard told radio station LBC that it had taken place at a testing range off the north coast of Scotland.
The website Navy Lookout said that XV Excalibur had been spotted at Kyle of Lochalsh last week, suggesting the trial may have taken place at the nearby British Underwater Test and Evaluation Centre (BUTEC) although this has not been confirmed.
"This is a really important moment in our journey toward building a hybrid navy," Pollard told LBC, referring to combining crewed ships with uncrewed and autonomous vessels.
He said that it would help secure the North Atlantic, "especially against those nations that wish to do us harm, like Russia."
Cancian from CSIS said: "it's a long road from a prototype demonstration to serial production—but the demonstration will signal intent and future capability."
The MOD said last December that Excalibur was classified as an Extra-Large Uncrewed Underwater Vehicle (XLUUV). It was built by Plymouth-based MSubs and developed by the UK’s Submarine Delivery Agency (SDA) as part of the Royal Navy's Project Cetus.
As a 12-metre experimental vessel with a displacement of 19 tonnes, it is the largest uncrewed underwater vessel ever trialed by the Royal Navy.
Following three years of development, Excalibur was named and unveiled at a ceremony at the Royal Naval Base in Devonport in May 2025 ahead of two years of sea trials.
The U.K. and Australia undertook a joint test-drive of Excalibur in 2025 as part of Exercise Talisman Sabre.
An operating center in Australia took remote control of the vessel, in what the British Royal Navy touted as showing how the U.K. can operate uncrewed systems interchangeably with Australia.
Navy Lookout reported that Excalibur has no torpedo tubes, but a large central payload bay and there are doors at the top and bottom.
However, it said that the 5.8-meter-long (16 feet) Mk 48 torpedo was too long to fit in the standard central payload bay, so during the latest trial, this may have been released from a cradle attached to the bottom of the hull.
Pollard said that firing torpedoes from uncrewed systems as well as Astute-class hunter-killer submarines showed "a substantial increase in our lethality."
What Is AUKUS?
The MOD statement described the Excalibur trial as "a significant breakthrough for Euro-Atlantic security and NATO’s undersea advantage" and touted the cooperation of AUKUS, the trilateral defense and security partnership between Australia, the United Kingdom, and the United States.
Announced, on 15 September 2021, the AUKUS partnership was considered as a response to the perceived threat of China to the Indo Pacific region.
It consists of Pillar 1, which focuses on Australia acquiring nuclear-powered attack submarines and the rotating U.S. and UK nuclear-powered attack submarines in Australia. It also has Pillar 2, which involves collaboration in areas like undersea capabilities, AI, and electronic warfare.
AUKUS partners announced on May 30 this year, the first Pillar II signature project to develop payloads and enabling systems for uncrewed undersea vehicles (UUVs).
Contact Newsweek editors on this story: Matthew Robinson and Tony Phillips.
Update, 09/23/2026 8:06 a.m. ET: this article was updated with comment from Mark Cancian, senior adviser at the Center for Strategic and International Studies (CSIS).
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