‘Sea Hunter’ prepares to seek and, eventually, destroy.
The U.S. Navy has christened the world’s largest unmanned surface vessel, a 132-foot submarine-hunting robotic warship that the Pentagon hopes to eventually field in large numbers. The unarmed prototype—dubbed “Sea Hunter”—is capable of plying large swaths of ocean searching for potential undersea threats, all without a human crew or even direct human intervention.
“It’s not just a remote controlled boat,” DARPA program manager Scott Littlefield told reporters earlier this week ahead of Sea Hunter’s christening. While Sea Hunter’s human handlers will oversee the vessel’s operations from afar, the ship will navigate itself through open waters relying on its own sensors and programming. In other words, “the human being is in control, but not joy sticking the vessel around,” he said.
The Defense Advanced Research Projects Agency, or DARPA, which developed the vessel along with Virginia-based Leidos ldos , calls it the Anti-Submarine Warfare Continuous Trail Unmanned Vessel, or ACTUV (pronounced, “active”). Its anti-submarine role serves a growing need for the U.S. Navy as countries like China and Russia introduce quieter and stealthier diesel-powered submarines. But Pentagon officials say an autonomous surface vessel of ACTUV’s size and capability could fulfill a number of roles for the Navy including mine detection and clearing. The deployment of fleets of robotic warships would mark a significant shift in the way autonomous systems are used by the military at sea, and could potentially alter the fundamental makeup of the future U.S. Navy fleet.
Get Data Sheet, Fortune’s technology newsletter.
During its upcoming trials humans will remain onboard the Sea Hunter as a safety net, but once the system’s reliability is established an onboard human presence will no longer be necessary. The operator station visible atop the vessel is removable, and the interior of the ship, while accessible for maintenance, is not designed to accommodate a crew. It will carry no weapons, though Pentagon officials acknowledge that future autonomous warships certainly may. Rather than proving that Sea Hunter itself is ready for war, the two-year test period will prove the technologies onboard, including that the autonomous navigation and piloting technologies underpinning the ACTUV program are ready to be used by the Navy in real-world scenarios.
While the Navy currently deploys unmanned systems—both in the air and in the water—they are largely remotely piloted and operate within close proximity to manned vessels. Sea Hunter can carry 40 tons of fuel and cover 10,000 nautical miles cruising at 12 knots, allowing it to operate far from conventional fleets or coastlines for two or three months at a time with no direct human intervention. Its trimaran design–the central hull flanked by outboard pontoons–provides stability in all kinds of weather and can survive waves up to 20 feet high, making the robotic ship effective in conditions that manned surface ships would typically avoid.
Sea Hunter will detect other surface ship traffic or obstacles via cameras and other onboard sensors, making its way across the ocean in much the same way Google’s self-driving cars operate amid other vehicles on the road. Additional sensors will scan the depths below, looking (and listening) for potential undersea threats.
In speed tests, the vessel has reached 27 knots—or roughly 31 miles per hour—fast enough to keep up with any conventional submarine the Navy deems worth tracking. That mix of speed, endurance, and autonomy could let vessels like Sea Hunter track subs for months at a time at a fraction of the cost of a crewed sub-hunting vessel. The Pentagon thinks it could produce ships like Sea Hunter for $20 million dollars each and operate them for between $15,000 and $20,000 a day (compared with well over $1 billion dollars for a modern Arleigh Burke class destroyer, which can cost hundreds of thousands of dollars per day to operate).
Meanwhile the need for better sub-hunting capabilities is very real. China, in particular, has upped its undersea warfare game substantially over the past decade, and occasionally reminds the U.S. Navy of the fact. National security news site Defense One notes two such incidents in recent years—one in 2006 when a Chinese sub surfaced just a few miles from the aircraft carrier USS Kitty Hawk, and another incident in October when a Chinese attack submarine first tailed the aircraft carrier USS Ronald Reagan off the coast of Japan and then executed a maneuver simulating a missile attack.
For more about robotic autonomy, watch:
Chinese muscle-flexing aside, something like Sea Hunter fits squarely into an ongoing Pentagon strategy aimed at offsetting military manpower with better technology, including what the Pentagon likes to call “manned-unmanned teaming.” Future unmanned warships based on ACTUV technologies could operate in conjunction with manned ships as well as manned and unmanned aircraft to detect threats, assign targets, share information, and generally keep crewed vessels out of harm’s way.
“I have been waiting for this day for a long time,” Work, one of the offset strategy’s biggest champions, said at Sea Hunter’s christening ceremony. “We are in a period of incredible technological flux. Advances in A.I., autonomous control systems, advanced computing, big data, learning machines, intuitive visualization tool, metamaterial, miniaturization are leading us toward great human-machine collaboration, in business and manufacturing, and in warfare.”
Those remarks echo similar comments Work made last month in which he described a relatively near-term future in which unmanned and autonomous F-16 fighter jets would fly alongside manned F-35 fighters in combat. While that future is a little farther away, Work says he hopes to see the Sea Hunter join the Navy’s Japan-based 7th fleet for further testing after its trials with DARPA and the Navy wrap up in a couple of years. After that, fleets of autonomous warships could be on the water in relatively short order.
“I would like to see unmanned flotillas operating in the western Pacific and the Persian Gulf within five years,” Work told Reuters.