US and UK navies launch Mk 48 torpedo from uncrewed submarine in a first for allied undersea warfare

On September 13, 2026, the US Navy and Royal Navy launched an American Mk 48 heavyweight torpedo from the British XV Excalibur uncrewed submarine off Scotland under Project Broadsword. The roughly 3,700-pound weapon was mounted externally because Excalibur has no torpedo tubes. The project was approved just seven months before the test.

• The ~3,700-pound Mk 48 torpedo was mounted externally beneath XV Excalibur's hull
• The test took place on September 13, 2026, in Scotland under Project Broadsword
• Project Broadsword was approved in February 2026, with integration completed in seven months
• The next phase, Project CUTLASS, will use Anduril's Dive-XL platform