The proof-of-concept launch took place at the British Underwater Test & Evaluation Center (BUTEC) in Scotland, according to an official U.S. Navy press release. The exercise demonstrated the mechanical, electrical, and software integration of an American kinetic payload onto a British autonomous platform, proving weapon interchangeability between allied forces.
“This successful test marks a historic first for allied undersea warfare,” said Chief of Naval Operations Adm. Daryl Caudle. “Proving that we can seamlessly launch a U.S. heavyweight torpedo from a Royal Navy autonomous underwater vehicle validates our shared vision for true interchangeability.”
The launch was conducted under AUKUS Pillar 2, a military partnership between the United States, the United Kingdom, and Australia aimed at accelerating advanced defense technologies such as artificial intelligence, quantum computing, and autonomous underwater systems. The project, designated Project Broadsword, received approval in February 2026 from the Department of the Navy Rapid Capabilities Office and was executed in collaboration with OPNAV N97, the Royal Navy, the Defense Innovation Unit, Naval Undersea Warfare Center Keyport, and several industry partners. From approval to trials took just seven months.
The Mk 48 is a heavyweight anti-submarine and anti-surface torpedo typically launched from fully manned submarines. XV Excalibur is the Royal Navy’s Extra-Large Uncrewed Underwater Vessel (XLUUV), designed to operate autonomously or via remote control. Because Excalibur lacks traditional internal torpedo tubes, engineers attached the 2-ton torpedo externally using a specialized cradle beneath its hull.
The U.S. Navy confirmed that following the success of Project Broadsword, it will “continue aggressive follow-on acceleration with Project CUTLASS,” in collaboration with its partners. The next phase will utilize the Anduril Dive-XL platform to tackle advanced payload integration.