DARPA Unveils Unmanned Ship 'Defiant' Designed for Long-Duration Operations

The U.S. Defense Advanced Research Projects Agency (DARPA) has launched the USX-1 Defiant, a medium-sized unmanned surface vessel (USV), as part of its No Manning Required Ship (NOMARS) program.

USX-1 Defiant has officially launched! The No Manning Required Ship (NOMARS) program has built a vessel designed to operate autonomously for long durations at sea. #USV For more info and images: https://t.co/n2pIDZyata pic.twitter.com/Dijsxy0EIO

— DARPA (@DARPA) March 4, 2025

In a press release, DARPA reported that the construction of the $25 million worth vessel, developed by Serco, was completed last month.

The 180-foot, 240-metric-ton Defiant is designed to operate autonomously for long durations at sea. While the exact role of Defiant was not disclosed, larger USV concepts from Serco have been proposed as low-cost missile platforms supporting naval operations.

Unlike previous USVs, which were converted from existing manned vessels, Defiant was designed from the ground up to operate without human crew members.

Serco’s design includes space for a BAE Adaptable Deck Launcher and a mission container, which could allow for weapons integration.

According to DARPA, the NOMARS program seeks to redefine traditional naval architecture by designing a seaframe (the ship without mission systems) from the ground up, with no provision or expectation for humans on board.

By eliminating human considerations from the design process, the program aims to showcase significant advantages, including reduced size and cost, enhanced at-sea reliability and improved hydrodynamic efficiency.

According to DARPA, the Defiant has already been transported from the shipyard to the waters. It is scheduled for two months of in-water testing, both dockside and at sea before moving into its full operational demonstration in spring.

It is unclear where the vessel is currently docked, but a recent post on Reddit reported that residents in Washington state observed the Defiant being towed by a tug through the Saratoga Passage in Puget Sound, just north of Seattle.