The United States and United Kingdom successfully launched an American MK 48 torpedo from a British undersea drone on Sept. 13, 2026, in what the U.S. Navy called a “historic first.” The test took place at the British Underwater Test and Evaluation Center in Scotland and showed that a U.S. weapon could be fitted to and released from a British uncrewed vehicle.
The project was implemented in less than seven months as part of the trilateral security partnership AUKUS, which also includes Australia. The Navy announced the successful test in a statement on Tuesday, Sept. 22.
During the test, a 19-foot-long, 3,744-pound MK 48 torpedo was strapped to the underside of the XV Excalibur, a British uncrewed underwater vehicle, and released. The Navy said the test confirmed that the torpedo and drone worked together mechanically and electronically, including their software, “proving that allied forces can rapidly achieve weapon interchangeability.”
The MK 48 is an acoustic-homing torpedo used by all classes of U.S. submarines. It carries a 650-pound warhead and has sophisticated sonar, digital guidance and control systems, and digital fusing systems, according to the Navy.
The XV Excalibur, unveiled in May 2025, is 39 feet long, displaces nearly 21 tons, and is Britain’s largest uncrewed undersea vehicle, according to the U.K. navy.
Adm. Daryl Caudle, chief of naval operations, said in the statement: “We are increasing the flexibility, scale and combat power of our combined forces and ensuring they are ready to meet the strategic demands of tomorrow.”
Luke Pollard, U.K. minister for defense readiness and industry, told a British radio station that the test also served as notice of NATO capabilities “in securing the north Atlantic, especially against those nations that wish to do us harm, like Russia.” European leaders believe the Kremlin is targeting undersea infrastructure, such as communication lines and pipelines, and blame Russia for a series of recent cable cuttings and other gray-zone attacks.
The joint initiative directly supports an AUKUS mandate to quickly develop and field new asymmetric capabilities to bolster collective defense, the Navy statement said. AUKUS focuses on technology sharing in the Indo-Pacific to deter China. The agreement includes regular rotations of U.S. and U.K. nuclear-powered submarines to Australia and calls for the sale of at least three used U.S. Virginia-class submarines to Australia, followed by construction of a new class of nuclear-powered submarines for Australia and the U.K.
Following the successful deployment, the Navy and its international partners will work on integrating other equipment, improving how the vehicles are controlled, and developing ways to use them in operations, the service said.
“We are not waiting 10 years for a single bespoke platform,” Vice Adm. Seiko Okano, director of the Navy’s Rapid Capabilities Office, said in the statement. “We are pioneering a modular, software-defined, open-systems approach that integrates allied hardware with commercial innovation to rapidly scale distributed lethality.”
Sources: USNI News · Stars and Stripes