Two sister ships, measuring 193 feet in length and 32 feet in width, arrive in Japan.
They have cargo-carrying capacity for containers and advanced systems, including Lockheed Martin's Aegis combat system.
Both ships have conducted test firings of SM-6 interceptor missiles.
Originally designed for offshore oil and gas support, they now have various modifications, including satellite communications and sensors.
These ships are part of the Ghost Fleet Overlord program to integrate unmanned vessels into the U.S. Navy fleet.
They were commissioned by the U.S. Navy as part of a Department of Defense initiative for autonomous navigation technology.
The vessels were built by Leidos and Gulf Craft in the U.S.
The visit to Japan's Yokosuka port signifies evolving defense cooperation between the U.S. and Japan.