The US Navy says parts on its Virginia-class attack submarines are breaking sooner than expected

US Navy leaders acknowledged a problem with the service's Virginia-class fast-attack submarines on Tuesday, telling lawmakers that parts are failing much sooner than expected.

"The Navy is aware there are some challenges with some of the Virginia-class supply chains," acting Secretary of the Navy Thomas Harker told the Senate Armed Services Committee.

"There are parts on the Virginia class that we thought were going to be life-of-the-submarine parts, and they are failing more quickly than we originally envisioned," Harker said, adding that the service's sub crews and parts support are having to go back in and find replacement parts.