Australia, Japan and the US close a two-way underwater drone link at Keen Sword

Australia, Japan and the United States linked autonomous maritime systems through one underwater communications network during Exercise Keen Sword 27 in Japan, Australia's Department of Defence said on 3 November 2026. Defence described the activity as the first trilateral warfighting experiment of its kind held in Japan and said it connected systems from all three nations through a single underwater network.

In the reported chain, a Japanese REMUS 620 unmanned underwater vehicle sent positional information to Australia's Rock Lobster underwater communications node. Rock Lobster passed the data to a United States gateway, which relayed it to a United States ground station. A command signal then returned through the same network to the vehicle, closing a two-way loop across Australian, Japanese and United States systems.

Defence Science and Technology Group helped design and deliver the experiment, which brought together military operators, scientists, engineers and technical specialists under realistic exercise conditions. Brice Mitchell of the group said the trial showed new levels of trilateral interoperability in an operationally relevant setting by integrating Australian, Japanese and United States technologies.

Captain Nakashima Junta of Japan's Joint Staff said the activity marked the first such trilateral experiment in Japan. Colonel Jeffrey Newcamp of US Pacific Command said exercises of this kind help move advanced science and technology concepts from the laboratory toward the tactical edge, and help joint forces keep tools needed for a free and open Pacific region.

Rock Lobster is a deployable underwater acoustic communications relay developed with the Royal Australian Navy and Defence Science and Technology Group. Radio links barely work under water, so acoustic relays move data between submerged vehicles and surface or shore networks. Defence did not publish range, data rate, latency, depth or encryption details for the Keen Sword trial, and it did not name the United States gateway system used.

Keen Sword 27 ran from 19 to 29 October 2026 as the Japan-United States field training series, with partner contingents including Australia. The underwater communications disclosure came after the exercise window closed and focuses on a technology trial rather than surface warship movements during the same series.

Independent defence reporting on 3 November restated the same four-step chain and the same official quotes. Those accounts treated the announcement as evidence of a reported communications link rather than proof that allied underwater fleets can already exchange every mission message in routine operations. No measured performance figures were released with the exercise disclosure.

Independent accounts also noted that shared acoustic links matter for partners that field different underwater vehicles and command software, while stressing that the Keen Sword disclosure shows one configured chain worked in the exercise setting rather than a finished multinational undersea network.