Maintenance problems forced an amphibious assault ship to return to California last week, just days into its first deployment in five years.

The USS Boxer left San Diego, its homeport, on April 1 for the Indo-Pacific, but turned back toward home Thursday for “additional maintenance in support of its deployment,” according to a statement 3rd Fleet made to several news outlets.

“USS Boxer will resume its deployment in the near future,” the statement said.

Third Fleet didn’t elaborate on the maintenance problem, but USNI News reported Thursday it was related to the ship’s rudder. Repairs could take up to three weeks, according to the report, which cited an unnamed defense official.

A spokesperson for 3rd Fleet did not respond to an email and phone call requesting comment Sunday afternoon.

The 843-foot Boxer is the flagship of an amphibious ready group that includes the 15th Marine Expeditionary Unit from Camp Pendleton, Calif., and two other ships, the amphibious transport dock USS Somerset and landing ship dock USS Harpers Ferry.

The group also includes new amphibious combat vehicles designed to replace the amphibious assault vehicles in which eight Marines and a sailor drowned off Southern California in July 2020.

The Boxer was already under scrutiny following significant mechanical issues that delayed its deployment multiple times.

A Navy review of three separate engineering failures found that “bad leaders, a complacent crew and maintenance cost-cutting by the Navy” prevented the ship from deploying for more than a year, KPBS, the Public Broadcasting Service station in San Diego, reported March 4, citing Navy investigations obtained via the Freedom of Information Act.

The Boxer last deployed in 2019 to the Persian Gulf amid flaring tensions with Iran.

In 2020, BAE Systems received a $200.3 million contract to perform approximately 18 months of maintenance and modernization, with work scheduled to begin in June 2020 and conclude by December 2021, BAE Systems announced in April 2020.

That maintenance ultimately lasted more than two years, with the ship going to sea again in June 2022, according to a photo the Boxer posted that month to the Defense Visual Information Distribution Service.

However, overhauled engine components called forced draft blowers failed in August 2022, prompting additional repairs, which also failed, KPBS reported.

Issues with the ship’s boiler and its engine’s main reduction gear arose in the following months, KPBS reported.

The Navy’s chief of naval operations, Adm. Lisa Franchetti, said she’d ordered a “deep dive” investigation into the issues, Military.com reported April 8.

The Navy is facing an estimated $1.8 billion backlog in maintenance for surface warships, according to a 2023 report from the Government Accountability Office.

The GAO also found that ship casualty reports — descriptions of events that impair a ship’s ability to conduct its primary mission — were also on the rise, primarily with littoral combat ships and Wasp-class amphibious assault ships like the Boxer.

Wasp-class ships in fiscal year 2011 experienced 18 level-three and level-four casualty reports, the highest categories. In fiscal year 2021, that rose to 61 casualty reports.

Freedom-class and Independent-class littoral combat ships saw the second-highest increase, rising from 18 and 11 reports in 2011 to 44 and 37 reports, respectively, according to the GAO.

In 2020, the Freedom-class littoral combat ship USS Detroit was forced to cut a counternarcotic operation short after a critical component in its propulsion system failed.