WASHINGTON — The Navy is making plans to reduce the American presence in the Persian Gulf by the end of the summer to a single carrier group, down from the two carrier groups now in the Gulf.

The preparations to reduce the American presence in the Persian Gulf, off the coast of Iran, come as a third carrier group, the USS Enterprise, is set to arrive this week. But just as the Enterprise arrives, the USS Nimitz is planning to redeploy. Meanwhile the remaining carrier group, the USS John Stennis, is slated to leave the Gulf by summer’s end.

In the standoff between Iran and America, the decision to reduce the American carrier presence in the Persian Gulf indicates a softer line. Already, robust proposals inside the administration to designate Iran’s Revolutionary Guard a foreign terrorist entity have run into bureaucratic resistance from the State Department and Pentagon civilian leadership. At the intelligence level, comments are now being sought on the prospects of a back channel to Iran’s former president, Ali Akbar Hashemi Rafsanjani. Mr. Rafsanjani is a rival of President Ahmadinejad, who ascended to power in 2005 and has threatened to destroy Israel.

For now, America is focused on the United Nations and a third sanctions resolution at the Security Council.

Yesterday, a spokesman for the U.S. Navy, Lieutenant Bashon Mann, said the arrival of the USS Enterprise should not be understood as an escalation in the Gulf. “That is not going to happen,” he said. “The Enterprise is doing a one-for-one swap with the Nimitz. They are big ships, they are traveling with their strike groups, they cannot turn on a dime so to speak, but there won’t be an overlap. People will say there will be these overlaps. That means there will be three carriers, but that is incorrect.” The Drudge Report yesterday featured a story from Reuters announcing the arrival of the third carrier group.

Another Defense Department spokesman who asked for anonymity confirmed yesterday that by the end the summer, the Navy will have only one carrier in the Gulf.

“Going up from 1.0 to 2.0 was a big strain on the Navy,” the deputy director for research at the Washington Institute for Near East Policy, Patrick Clawson, said this week. “Three out of eleven carriers is a hell of a commitment. We have to maintain carriers near Korea. And carriers are an extraordinary form of warfare, which requires a lot of training. One always needs carriers for training.”

Another administration official said the decision to leave one carrier in place was an effort to lower tensions with Iran. This official added, however, that should President Bush order air strikes against the Iranians, American bombers could launch from Iraq, Turkey, and Afghanistan.

President Bush sent USS Stennis to the Gulf in February following the high-profile detention in Irbil, Iraq of five men alleged to be members of Iran’s Quds Force. The commanding general of American forces in Iraq, General David Petraeus, earlier this year accused the Quds force of masterminding the assassinations of American soldiers in Karbala.

Release of the five members of the revolutionary guard has been a key demand of Iran’s ambassador in Baghdad, Hassan Kazemi Qomi. The State Department has also argued internally for the release of the five men, but has been refused by General Petraeus on the grounds that all five are threats to coalition and Iraqi soldiers.

In May, America’s ambassador in Baghdad, Ryan Crocker, held meetings with Mr. Qomi, in part to explore the possibility of joint security cooperation between America and Iran, but also to confront the ambassador with evidence of Iran’s role in aiding the terrorist insurgency.

For now, the main focus of American diplomacy with Iran will be through the United Nations. Today the deputy director of the International Atomic Energy Agency, Olli Heinone, is scheduled to arrive in Tehran for talks with Iran’s top nuclear negotiator, Ali Larijani, on the remaining questions the Islamic Republic has yet to answer concerning its entire nuclear program.

Iran has according to some estimates already placed at least 1,500 centrifuges at its Natanz facility and has begun the process for enriching nuclear fuel. Israel, the state most threatened by an Iranian A-bomb, now estimates that Iran could have a nuclear weapon as early as 2009.

The spinning of those centrifuges is an explicit rejection of Iran’s earlier agreement with England, France, and Germany to halt fuel enrichment during negotiations with the United Nations. This month, the director of the International Atomic Energy Agency, Mohammed ElBaradei, proposed a plan whereby Iran would freeze its enrichment activities in exchange for a freeze of further sanctions. The Bush administration has rejected the formula.