U.S. Spends $60 Million to Hunt Nuclear Submarines With Civilian Crews

By Marcus Boone · August 9, 2026

Nuclear and diesel submarines are tracked by civilian mariners posing as peaceful oceanographers in a global dragnet stretching from Glasgow to Yokohama.

T-AGOS ships are not commissioned warships. They are "Auxiliary Oceanographic Survey ships," a designation that suggests a peaceful study of the seabed rather than a global dragnet for nuclear and diesel submarines. They are manned by civilian mariners under contract to the Military Sealift Command and operated by civilian "operations personnel" contracted to SPAWAR. Even the paint on their stacks—blue and gold bands—marks them as "United States Naval Ships" rather than the "United States Ships" that comprise the commissioned fleet.

The FAS Intelligence Resource Program page for the Surveillance Towed-Array Sensor System (SURTASS) records the specifics of this operation. It describes a system designed for the "mobile detection, tracking, and reporting of submarine contacts at long range." For decades, the U.S. relied on SOSUS arrays, fixed sensors on the ocean floor. But as those arrays were placed in "standby status," the burden of undersea surveillance shifted to the SURTASS fleet. The result is a mobile, tactical arm of the Integrated Undersea Surveillance System, a worldwide network of ships and shore sites that turns the open ocean into a monitored grid.

Non-Military Personnel

The government’s insistence on the "non-military" nature of SURTASS is a useful semantic shield. By staffing the mission equipment with contractors and civilian mariners under the operational command of Commander Undersea Surveillance (CUS), the program operates in a gray space. These ships are non-combatants, yet their sole purpose is "submarine hunting patrols."

The record details three classes of vessels used in this hunt. The Stalwart class, built in Tacoma, Washington, were the early workhorses. Some of these have since been repurposed for "drug interdiction forces," a pivot that allows the government to frame these surveillance assets as tools of law enforcement. Then came the Victorious class, utilizing a Small Waterplane Twin Hull (SWATH) design to ensure stability in rough waters while towing their sensors at low speeds.

Finally, there is the Impeccable class. These vessels, built in Tampa and Gulfport, are larger and heavier to accommodate the Low Frequency Active (LFA) system. The cost of this escalation is evident in the files: the lead ship of the T-AGOS 23 class carried a price tag of $60,000,000, though its delivery was plagued by "extensive delays" and "shipyard problems," pushing its arrival to the end of 1998.

Document imagery from irp.fas.org From the files: irp.fas.org

Low Frequency Active Sonar

For years, the SURTASS fleet relied on passive acoustic data collection—essentially listening for the sounds made by foreign vessels. But as submarines became quieter, the government developed the Low Frequency Active (LFA) upgrade. Unlike the passive arrays, the LFA is an "active adjunct," meaning it does not just listen; it transmits. It uses a large source array to send powerful active sonar pulses into the deep, designed to detect "even quieter threats in the future."

This active transmission transforms the ship from a listener into a broadcaster. The FAS records note that a prototype LFA system was even installed on a leased commercial vessel, the Cory Chouest, to serve as an interim asset. The transition to active sonar is framed as a technical necessity for "littoral warfare" and shallow-water operations, but it represents a fundamental shift in how the government projects its presence in the undersea domain.

To manage this data, the program relies on a series of software "Builds." Build #1 introduced automated line trackers and nuclear source auto-detectors. Build #2 added "diesel Full Spectrum Processing." By Build #3, the system achieved "automated localization and tracking." The humans on board are increasingly reduced to monitors for an automated process of classification and detection.

Document imagery from irp.fas.org From the files: irp.fas.org

Glasgow, Rota, and Yokohama

The reach of the SURTASS network is global, operating out of a series of "remote facilities" that serve as bases for the mission. While the central hub is in Norfolk, Virginia, the ships routinely operate from ports in Glasgow, Scotland; Rota, Spain; Yokohama, Japan; and Pearl Harbor, Hawaii. Pacific operations are coordinated through the IUSS Operations Support Detachment in Pearl City.

This global footprint allows the U.S. to maintain a persistent, mobile presence in virtually every strategic waterway. The FAS mirror mentions that the program is constantly seeking "ports of opportunity" to sustain its operations. The network is designed for "expandability and flexibility," utilizing an open system architecture to lower life cycle costs while increasing the resolution of its spectrum analysis.

This technological expansion has not come without external costs. The documents reference a legal challenge to the use of the Low Frequency Active sonar, The Cetacean Community v. George W. Bush. The lawsuit attempted to stop the Navy's use of LFA, citing the impact of active sonar on marine mammals. In October 2004, an appeals court ruled that cetaceans do not have standing to sue the government to challenge the Navy's use of SURTASS / LFA.