On September 13, 2026, the U.S. Navy and the Royal Navy conducted a joint test in which the Excalibur uncrewed underwater vehicle successfully launched a U.S. Mk 48 heavyweight exercise torpedo.
For both countries, this can be seen as a first step toward creating their own fleets of armed uncrewed underwater vehicles capable of deploying different types of weapons. For Ukraine, which is currently at war, the development is also conceptually interesting, at least in terms of looking for tools that could potentially be used to finish off russia's Black Sea Fleet at its base in Novorossiysk.
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According to The War Zone, Excalibur is a British-developed uncrewed underwater vehicle that was first unveiled in 2025. It was developed by the British company MSubs under Project Cetus.
The vehicle is 12 meters long and has a displacement of 19 tonnes. Excalibur has an internal payload bay, but it is reportedly not large enough to accommodate heavyweight 533 mm torpedoes such as the Mk 48.
Therefore, integrating the Mk 48 into Excalibur's weapon suite required the U.S. Navy to launch a separate project known as Broadsword. The work took less than seven months. The technical solution was relatively straightforward: the torpedo was mounted externally beneath the Excalibur's hull.
The range at which the Mk 48 was launched, the target-detection and targeting chain, and the fire-control system used for the test have not been disclosed. The work was carried out as part of AUKUS Pillar 2, the trilateral defense partnership between the United States, the United Kingdom and Australia.
Defense Express would add that the successful launch of a torpedo from an uncrewed underwater vehicle by the British and U.S. navies clearly demonstrates that a similar weapons system could eventually be developed for Ukraine's Defense Forces. Such a capability could potentially provide a way to conduct covert attacks against surviving russian Black Sea Fleet vessels confined to their base in Novorossiysk.
It is worth recalling that in December 2023, questions arose over why a mini-submarine was being built 600 km from the Black Sea and what such a weapon could potentially be used for. However, it still remains unclear who the DG-160 project submarine was actually being built for.
Ivan Kyrychevskiy, serviceman of the 413th Raid Regiment of the Unmanned Systems Forces of Ukraine and weapons expert at Defense Express.
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