The U.S. Navy’s attack submarine maintenance has been completed on schedule just 11% of the time over the last decade, according to a Government Accountability Office (GAO) report released on August 27. The analysis covers depot-level maintenance at four public naval shipyards—Portsmouth Naval Shipyard, Norfolk Naval Shipyard, Puget Sound Naval Shipyard, and Pearl Harbor Naval Shipyard—from fiscal years 2016 through 2025. During this period, maintenance delays occurred 89% of the time, with 3,040 days (more than eight years) of delays recorded from 2016 to 2020 and 3,454 days (nearly 10 years) from 2021 to 2025. The average maintenance period for an attack submarine increased from 744 days (2016–2020) to 809 days (2021–2025).
The delays have incurred $3.4 billion in costs to sustain crews and submarines during idle periods, with an additional $3.1 billion projected over the next five years if no mitigation occurs. The service has also lost more than 15,000 operational days due to maintenance backlogs, with an estimated 14,000 additional days at risk from 2026 to 2030. The GAO noted that while active idle time—periods when submarines cannot operate due to maintenance—has seen some reduction, inactive idle time—when submarines await decommissioning—has grown and is expected to worsen.
Key Shipyard Challenges
The four public shipyards responsible for most attack submarine maintenance have faced persistent delays, with Norfolk Naval Shipyard and Pearl Harbor Naval Shipyard frequently cited for extended backlogs. For example, the USS Pasadena entered inactive idle status on January 1, 2025, but is not scheduled to begin decommissioning until November 15, 2028, due to shipyard limitations. The GAO estimated this delay alone will cost the Navy over $300 million. The report also highlighted that 15 attack submarines are projected to enter inactive idle status between fiscal years 2026 and 2030, further straining resources.
Fleet Readiness and Operational Impact
The Navy’s Fleet Response Training Plan outlines an 18-month operational cycle for attack submarines, including 12 months of training and certification followed by a six-month deployment. However, maintenance delays have disrupted this schedule, leading to operational gaps and increased costs. The GAO warned that without intervention, the Navy could face additional delays and financial burdens, particularly as older Los Angeles-class submarines are decommissioned over the next five years.
The report emphasized that while some progress has been made in reducing active idle time, inactive idle time remains a growing concern, with potential long-term implications for fleet readiness. The Navy currently operates 44 attack submarines, which are critical for intelligence gathering and strike missions. The GAO concluded that the service has not fully addressed the underlying issues affecting submarine readiness.