After years of long and repeated deployments to the Middle East, the Navy's fleet of warships is behind on maintenance, possibly threatening the service's ability to meet future missions overseas.
That's according to a report released Monday by the Government Accountability Office, which found that the Navy bypassed some ship maintenance over the past 15 years to keep pace with the demands of multiple wars.
That's led to a backlog in work needed to keep the fleet going.
"These decisions have reduced the predictability of ship deployments for sailors and for the ship repair industrial base," the report said. "They have also resulted in declining ship conditions across the fleet and have increased the amount of time that ships require to complete maintenance in the shipyards."
The Navy has long been aware of the brewing problem. In 2014, it implemented a new training and maintenance cycle, starting with aircraft carriers, designed to ease the burden on its sailors and ships.
The strategy, known as the Optimized Fleet Response Plan, deploys ships less frequently -- once every 36 months instead of once every 32 months. The plan makes seven-month deployments the new standard, as opposed to six-month cruises that often stretched to eight months or longer. It also leaves more time for maintenance.
But the plan won't work if the Navy can't accurately predict how much work ships need or how long they'll need to spend in shipyards between deployments.
That's been a challenge.
Between 2011 and 2014, before the deployment cycle change, only one of nine aircraft carriers completed its time in the shipyard and returned to the fleet on schedule, the GAO found. Among the Navy's surface vessels, such as destroyers, cruisers and amphibious ships, only about one in four exited shipyards on time over that same period.
The new deployment cycle hasn't helped matters so far; each of the first three carriers to begin the new plan has needed more maintenance than expected and has been delayed rejoining the fleet.
A number of factors have led to the delays, according to the report, including unanticipated repairs, workforce inexperience and staffing shortages at the Navy's public shipyards, including Norfolk Naval Shipyard in Portsmouth.
In 2013, the aircraft carrier USS Dwight D. Eisenhower entered that shipyard for what was supposed to be a 14-month overhaul. But because much more work was needed than expected -- and because of poor shipyard performance -- the carrier spent nearly two years in the yard, almost twice as long as planned.
That forced the Navy to delay the Eisenhower's deployment, and the USS Harry S. Truman was sent in its place, bypassing some scheduled maintenance for that ship.
Maintenance delays limit the amount of time available for training and deployment, the report said, "thereby jeopardizing the Navy's ability to meet its goals."
As a result of the Eisenhower delay, for several weeks last fall the Navy didn't have a carrier on station in the Middle East to help wage the U.S. air campaign against the Islamic State group. It was the first time since 2007 the U.S. didn't have a carrier in the volatile region.
The GAO did not make any recommendations or cast blame in its review, which was requested by Congress.
The Navy is taking steps to "aggressively address" the challenges, said Capt. Jack Hanzlik, a spokesman for U.S. Fleet Forces command in Norfolk. That effort includes hiring more shipyard workers and improving maintenance planning.
"These hiring initiatives and processes ... will help us achieve the readiness we need to deliver," Hanzlik said in a statement.