The US Navy temporarily will have one aircraft carrier in the Gulf region instead of two because one of its ships has to undergo repairs, officials said Friday.

The announcement reflected the strain on the Navy's fleet since President Barack Obama decided to maintain two aircraft carrier groups at all times in the Gulf, a policy driven by concerns over tensions with Iran.

The carrier USS Nimitz was supposed to replace the USS Dwight Eisenhower "early next year" but mechanical problems with the Nimitz delayed its scheduled deployment and forced a change in plans, officials said.

Instead, the Eisenhower will return sooner than scheduled for two months and then head back to the Middle East, in what the Navy acknowledged was "an unusual move."

During the two-month break at the Eisenhower's homeport of Norfolk, Virginia, the Navy "will resurface the ship's flight deck and make it available to return and remain in the Middle East region for several more months," the Navy said in a statement issued this week.

While the Eisenhower's crew gets a break after a nearly 10-month deployment, the aircraft carrier USS Stennis will remain in the Gulf along with other American warships, including a Marine contingent led by the amphibious assault ship, the USS Peleliu.

The year-round two carrier presence was reduced to one in December 2010.

The United States has bolstered its presence in the strategic Gulf over the past year after Iran threatened to close the Strait of Hormuz if Western countries boycotted Iranian oil exports.

About one-fifth of the world's traded oil passes through the vital waterway.