Washington: The US Navy has said it will temporarily shrink its aircraft carrier presence in the Arabian Gulf area from two to one because of a mechanical problem with the USS Nimitz, a carrier based in Bremerton, Washington.

The Nimitz was scheduled to deploy in January to relieve the USS Dwight D. Eisenhower, but that will be put off until summer in order to complete repairs to its propulsion system. The problem was discovered while the ship was doing pre-deployment manoeuvres.

As a result, the Navy made the unusual decision to bring the Eisenhower home to Norfolk, Virginia, in December and resurface its flight deck so it can return to the Gulf area in February and remain for four months. That means that in December and January the USS John C. Stennis will be the only carrier in that area, although there are other naval forces there, including Marines aboard a three-ship contingent led by the USS Peleliu.

In announcing the moves, the Navy said none are related to the conflicts or any other security threats or contingency planning. They said it reflects wear and tear on the carrier fleet, which has been under enormous strain during more than 11 years of war.

The decision to leave a two-month gap in the normal two-carrier Navy presence was approved on Tuesday by defence secretary Leon Panetta, officials said. The carriers are a key feature of the US military strategy for the Middle East.

It will be the first such instance when the US Navy will be left with a single aircraft carrier in the Gulf region since at least December 2010, officials said.

The Stennis, which deployed from its home port of Bremerton in late August, is due to head home in March. The current plan calls for it to be replaced then by the USS Harry S Truman.