US, UK Navies Launch Inert Mk 48 From XV Excalibur in 'A Historic First for Allied Undersea Warfare'

The U.S. and Royal Navies tested an inert Mk 48 from XV Excalibur in Scotland, advancing AUKUS work on allied undersea integration (Credit: U.S. Navy)

The US Navy and Royal Navy launched an inert, recoverable Mk 48 Mod 4 heavyweight torpedo from Britain's XV Excalibur uncrewed submarine during a trial in Scotland on Sept. 13, 2026.

The proof-of-concept launch took place at the British Underwater Test & Evaluation Centre under Project Broadsword and Trial Iron. The Royal Navy said it was the first time one of its uncrewed submarines had successfully fired a torpedo.