US attack submarine repair delays cost billions, watchdog says

The effectiveness of the US Navy’s attack submarines has been undermined by a shortage of dry-dock space that contribute to maintenance delays of as long as four years, costing the service about $3.4 billion over the last decade, according to a new congressional audit.

The fleet of 44 Los Angeles-class and Virginia-class submarines has lost around 15,000 operational days since 2016 as vessels that are not certified to participate in combat missions wait near dry-dock berths — with their crew aboard — for needed repairs, the Government Accountability Office said in a declassified report released on Thursday.

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While attack submarines are seen as a key military advantage over China, the US’s main geopolitical adversary, the problem only looks set to worsen in the coming years, the report said.

“Our report found costly and lengthy maintenance delays since 2016 have eroded the readiness of the submarine fleet,” said Diana Maurer, the GAO official who supervised the work. “Over the past decade, these delays have cost the Navy — and taxpayers — billions of dollars, and meant fewer subs are available to meet national security needs.”

The maintenance logjam adds to the Navy’s current submarine woes, with lingering delivery delays on the first Columbia-class and new Virginia-class vessels. It also comes amid a period of heightened scrutiny for the service, which has seen extended deployments as part of the Trump administration’s military operations in the Middle East and off the coast of South America.

Reports of deteriorating conditions aboard the USS Abraham Lincoln on its recent deployment to the Middle East have fueled concerns from US lawmakers and a wave of negative publicity, while the Pentagon ousted Navy Secretary John Phelan in April.

The Navy has also been accused of unclear acquisition plans, failed vessel programs and been criticized for President Donald Trump’s costly so-called Golden Fleet of new Trump-class battleships — which would be the most expensive vessels ever built.

The backlog underscores a chronic shortage in US shipyards of dry docks to conduct the crucial maintenance, the GAO said, with many critics pointing out the growing shipbuilding prowess of China. The administration is moving to try and boost US shipbuilding with subsidies and tax breaks, Bloomberg Government reported this week.

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According to metrics cited in the assessment, the Navy lost the equivalent of two attack subs on patrol in 2025, when factoring in the amount of time a submarine waited to enter dry dock — what’s considered “active idle time” — and then for the delays undergoing the upkeep. The total equaled 753 days for the year — equaling about two vessels. In 2023, it was even worse: the Navy lost the operational equivalent of five submarines.

The GAO cited that reduction in waiting time — between 2023 and 2025 — as an improvement. “Although the US Navy has not eliminated the attack submarine maintenance backlog, it has made significant progress in reducing attack submarine active idle time,” it said.

Maintenance is performed at all four Navy shipyards: Norfolk, Virginia; Portsmouth, New Hampshire, which does the most work on submarines; Puget Sound in Washington State; and Pearl Harbor in Hawaii.