The US Navy’s dream of robot warships just got a whole lot closer to reality!

As announced last Friday, March 22, four companies are now in the fast lane to providing the Navy with its next-gen fighting machines on wheels—well, propellers—after acing some extremely tough engine tests.

Congress mandated the engine trials, which were a critical hurdle for companies competing for a piece of the Large Unmanned Surface Vessel (LUSV) program.

Each contender’s proposed engine system faced a demanding 720-hour test, simulating real-world conditions of a 30-day unmanned mission.