US Navy Submarine Backlogs Could Cost Billions and Sideline Attack Subs, GAO Says

A Government Accountability Office report says 15 US Navy attack submarines could enter inactive idle time from fiscal year 2026 through fiscal year 2030. Without mitigation, those submarines could accumulate more than 14,000 idle days and cost $3.1 billion to operate and support while providing no operational capability. The finding adds to broader readiness concerns tied to submarine maintenance delays.

The GAO said the Navy has already lost more than 15,000 operational days over the last 10 years because of maintenance delays and idle time on active attack submarines. Those delays resulted in an estimated $3.4 billion in costs to sustain crews and submarines that provided no operational capability. Active idle time refers to the period when a vessel is no longer certified to operate but has not yet entered maintenance, leaving the Navy paying for pier-side submarines.

The report cited the Los Angeles-class submarine USS Pasadena as a clear example of the problem. The vessel entered inactive idle status on January 1, 2025, but is not scheduled for decommissioning until November 15, 2028, because of limited shipyard capacity. The Navy told the GAO it will use the Pasadena as a training platform while it waits, but the delay will cost more than $300 million, according to the watchdog.

Nuclear-powered submarines undergo major maintenance, repairs, and decommissioning at four public shipyards, with some depot-level work possible at two private yards. The Navy and shipbuilders are pursuing efforts to increase capacity and invest in workforce and infrastructure, while an executive order directed the Navy and Department of Defense to establish a fifth public yard. The Navy is also considering pier-side reactor defueling, floating dry docks, crew transfers, and submarine service-life extensions, but the GAO said some options need more documentation, further study, or approval.