The trial took place in UK waters last week with US participation, as part of the AUKUS alliance which includes Australia. However, the information was only announced by the UK on 21/9/2025.

The British government hailed the test as a "major step forward in the future of submarine technology" for the three nations. It also provides "important breakthroughs" for Euro-Atlantic security and NATO's undersea operational advantage.

The Excalibur uncrewed submarine in a photo released on 5/1. Photo: Naval News

The weapon used was a heavy torpedo developed by the US and Australia, but British officials did not specify its name. This could be the Mk.48 torpedo, which has a warhead weighing nearly 300 kg, is nearly 6 meters long, and has a range of 20-75 km depending on launch conditions and variant.

Sidharth Kaushal, an expert at the Royal United Services Institute (RUSI), described this as a notable development. "Deploying weapons with significant destructive power shows that uncrewed systems can take on roles far beyond conventional reconnaissance missions," he stated.

The Excalibur uncrewed submarine at its launch ceremony in Devonport, UK in 5/2025. Video: BFBS Forces News

The UK Submarine Delivery Agency (SDA) handed over the Excalibur uncrewed submarine to the Royal Navy in 12/2025. At 12 meters long and with a 19-ton displacement, it is the largest uncrewed underwater vehicle the Royal Navy has ever tested.

Excalibur was launched in a ceremony in 5/2025 and participated in Exercise Talisman Sabre three months later. British operators controlled the Excalibur from a center in Australia, located over 16,000 km from the operational area.

Nguyen Tien (According to AFP, Naval News)