The US Navy is planning to build a fleet of 10 corvette-sized large unmanned surface vessels (LUSV) within the next five years that won’t carry any sailors.

As part of the fiscal year 2020 budget, the Navy asked for $400 million to build two LUSVs that are about 200 to 300 feet in length with a displacement of about 2,000 tons as a research and development program. The U.S. Navy’s budget director describes the ships as the service’s “Ghost Fleet.”

“The LUSV will be a high-endurance, reconfigurable ship able to accommodate various payloads for unmanned missions to augment the Navy’s manned surface force,” the official Request For Proposal (RFP) read. “With a large payload capacity, the LUSV will be designed to conduct a variety of warfare operations independently or in conjunction with manned surface combatants. The LUSV will be capable of semi-autonomous or fully autonomous operation, with operators in-the-loop (controlling remotely) or on-the-loop (enabled through autonomy).”

The “Ghost Fleet” will carry a variety of sensors to extend the Navy’s vision. The proliferation of supersonic anti-ship missiles, hypersonic missiles, and other fast-moving threats to U.S. Navy aircraft carriers and large amphibious ships makes it paramount to detect threats from as far away as possible. But the curvature of the Earth dramatically lowers the distance at which low-flying missiles and aircraft can be detected by the ring of cruisers and destroyers protecting high value targets.

The ships will also likely carry weapons, giving the fleet greater firepower and an asset commanders won’t hesitate to send on the most dangerous missions, since that won’t mean endangering the lives of sailors.

“Ghost Fleet” builds on the success of the Navy’s Sea Hunter program, an unmanned ship that recently traveled from the West Coast of the United States to Hawaii. Sea Hunter was 132 feet long and 140 tons, so the new large unmanned surface vessels are a major step up.

The US Navy is planning to procure a total of 201 unmanned vessels over the next five years including 135 Hydroid ML-18 Unmanned Undersea Vehicles (UUV), 10 small/ medium UUV, three large-diameter UUV, and nine extra-large UUV.

The US Navy is pursuing LUSV technology alongside directed-energy weapons, hypersonic and artificial intelligence as part of a push to confront emerging threats like that of China which has an advantage in the number of hulls, personnel and specialized anti-ship ballistic missiles.