Military News, Ministry of Defence News

Royal Navy’s Robot Submarine Controlled from 10,000 Miles Away

Plymouth, England – The Royal Navy has unveiled a bold vision of future warfare with the successful trial of its prototype robotic submarine, XV-Excalibur, which was remotely controlled from a command centre in Australia – 10,000 miles away.

The Extra-Large Uncrewed Underwater Vessel (XLUUV), developed by Plymouth-based MSubs under Project Cetus, carried out patrols at HMNB Devonport in July as part of the multinational Exercise Talisman Sabre. The operation demonstrated how robotic craft might one day augment Britain’s fleet of nuclear-powered attack submarines.

Illustration of the XV-Excalibur, a prototype robotic submarine designed for future warfare, featuring a streamlined body and various sensors.


Launched in May, the 39 ft-long vessel resembles the midget submarines used in the Second World War. With a beam of 7 ft and a displacement of 19 tonnes, it is dwarfed by conventional attack subs. Yet without the need to accommodate a crew, the vessel can be crammed with sensors, surveillance systems and modular payloads tailored for missions ranging from anti-submarine warfare to seabed operations.

Although unarmed for now, officials describe Excalibur as the most advanced uncrewed submarine in Europe. Its performance specifications – including propulsion system, speed and range – remain under wraps.

An infographic showcasing various major large and extra-large uncrewed underwater vehicles, including their designs and countries of origin.


The July trials fell under the UK/US/Australia “Maritime Big Play” exercise, part of the biannual Talisman Sabre drills involving 19 nations, with Brunei and Malaysia attending as observers. The test highlighted both the Royal Navy’s ambition to push unmanned warfare further and the deepening defence ties within the AUKUS security pact.

“This exercise demonstrates how we are exploiting the learning from our experimentation, by applying it to the Royal Navy’s growing arsenal of Uncrewed Underwater Vehicles; taking experimentation into the hands of the war fighter,” said Captain Keith Taylor, RN, the UK’s Senior Responsible Owner for Maritime Big Play.

A prototype robotic submarine, the XV-Excalibur, partially emerged from the water, showcasing its sleek design and advanced technology against a maritime backdrop.
Infographic illustrating European Extra-Large Uncrewed Underwater Vehicles (XLUUVs) showcasing various components and design features.

Project Cetus forms part of AUKUS Pillar II, the trilateral initiative between Britain, the US and Australia to share cutting-edge submarine technologies. Beyond Excalibur, it is intended to lay the groundwork for Australia’s future nuclear-powered AUKUS-class attack submarines.

The robot vessel, though modest in size, offers a glimpse of the silent fleet of the future – one in which submariners may be thousands of miles from the seas they patrol.