The U.S. Navy has confirmed that the USS John C. Stennis and USS Nimitz aircraft carriers and their strike groups have entered Gulf waters. (Xinhua Photo)

Two U.S. aircraft carriers on Wednesday entered Gulf waters, which was the first such deployment since the 2003 Iraq war, said reports reaching here from the Bahrain capital Manama.

The two aircraft carriers, USS John C. Stennis and USS Nimitz, and their strike groups entered Gulf waters off Iran's coast to "conduct missions in direct support of Operation Iraqi Freedom and perform Expeditionary Strike Force training," the Bahrain-based US Fifth Fleet was quoted as saying in a statement.

The U.S. Navy, meanwhile, denied the up-coming training exercises were related to the Iran standoff.

"The timing of this exercise is determined by the availability of forces, and is not connected to events in the region. This exercise is not directed against any nation," the statement stressed.

Tensions is high in the region over Iran's controversial nuclear program. The United States has accused Iran of trying to produce nuclear weapons and sought tougher UN sanctions against Tehran, while Iran says its nuclear program is for peaceful purposes only.

U.S. warships carrying 17,000 personnel enter the Gulf in a show of force off Iran's coast that navy officials said was the largest daytime assembly of ships since the 2003 Iraq war in this May 22, 2007 handout photograph. (Xinhua Photo)

U.S. warships carrying 17,000 personnel enter the Gulf in a show of force off Iran's coast that navy officials said was the largest daytime assembly of ships since the 2003 Iraq war, in this handout photograph taken May 22, 2007. (Xinhua Photo)

Editor: Yan