Navy has lost 15,000 operational days because of idle submarines, GAO reports

The Navy has lost 15,000 operational days on U.S. attack submarines due to maintenance backlogs and delays at shipyards, according to a new government report.

The Government Accountability Office said in the Aug. 27 report that the submarines are forced to spend idle time in port instead of being deployed or used for crew training because to long waits at shipyards.

“Delays resulted in an estimated $3.4 billion in costs to sustain crews and submarines” when not operational, the report said.

The report is an unclassified version of a classified report issued in April, the GAO said.

The GAO said it conducted the report because of the strategic importance of attack submarines.

“According to the U.S. Navy, its 44 attack submarines, as of fiscal year 2025, provide the United States an asymmetric advantage to gather intelligence undetected and attack enemy targets, among other missions,” the report states. “These capabilities make attack submarines some of the most requested assets by the global combatant commanders.”

The GAO report included “active idle time,” when submarine crews “must remain pier-side because they are no longer certified to conduct normal operations and cannot be inducted into a maintenance period.”

The GAO said the Navy has made inroads into cutting active idle time, but inactive idle time is growing worse.

Without significant changes, the report said that 15 attack submarines could enter inactive idle status between FY2026 and FY2030. The Navy could incur more than 14,000 additional days of inactive idle time, at a cost exceeding $3.1 billion, just to operate and support those inactive submarines.

The report said another problem is the long waits to decommission nuclear submarines, which may have cost $722 million from 2016 to 2025.

The GAO recommended the Navy fully evaluate alternatives to more efficiently decommission attack submarines and develop an attack submarine inactivation plan that reduces inactive idle time.

Maintenance on nuclear-powered attack submarines is done at Portsmouth Naval Shipyard, in Kittery, Maine; Norfolk Naval Shipyard, in Virginia; Puget Sound Naval Shipyard, in Bremerton, Wash.; and Pearl Harbor Naval Shipyard, in Hawaii.

Two shipyards where submarines are constructed can also do maintenance work: General Dynamics Electric Boat in Groton, Conn., and Huntington Ingalls Industries Newport News Shipbuilding in Newport News, Va.

The report says the Navy verbally concurred with GAO’s recommendations but did not provide written responses.