In a series of public statements in recent months, President Bush and members of his Administration have redefined the war in Iraq, to an increasing degree, as a strategic battle between the United States and Iran. “Shia extremists, backed by Iran, are training Iraqis to carry out attacks on our forces and the Iraqi people,” Bush told the national convention of the American Legion in August. “The attacks on our bases and our troops by Iranian-supplied munitions have increased. . . . The Iranian regime must halt these actions. And, until it does, I will take actions necessary to protect our troops.” He then concluded, to applause, “I have authorized our military commanders in Iraq to confront Tehran’s murderous activities.”

The President’s position, and its corollary—that, if many of America’s problems in Iraq are the responsibility of Tehran, then the solution to them is to confront the Iranians—have taken firm hold in the Administration. This summer, the White House, pushed by the office of Vice-President Dick Cheney, requested that the Joint Chiefs of Staff redraw long-standing plans for a possible attack on Iran, according to former officials and government consultants. The focus of the plans had been a broad bombing attack, with targets including Iran’s known and suspected nuclear facilities and other military and infrastructure sites. Now the emphasis is on “surgical” strikes on Revolutionary Guard Corps facilities in Tehran and elsewhere, which, the Administration claims, have been the source of attacks on Americans in Iraq. What had been presented primarily as a counter-proliferation mission has been reconceived as counterterrorism.

The shift in targeting reflects three developments. First, the President and his senior advisers have concluded that their campaign to convince the American public that Iran poses an imminent nuclear threat has failed (unlike a similar campaign before the Iraq war), and that as a result there is not enough popular support for a major bombing campaign. The second development is that the White House has come to terms, in private, with the general consensus of the American intelligence community that Iran is at least five years away from obtaining a bomb. And, finally, there has been a growing recognition in Washington and throughout the Middle East that Iran is emerging as the geopolitical winner of the war in Iraq.

During a secure videoconference that took place early this summer, the President told Ryan Crocker, the U.S. Ambassador to Iraq, that he was thinking of hitting Iranian targets across the border and that the British “were on board.” At that point, Secretary of State Condoleezza Rice interjected that there was a need to proceed carefully, because of the ongoing diplomatic track. Bush ended by instructing Crocker to tell Iran to stop interfering in Iraq or it would face American retribution.

At a White House meeting with Cheney this summer, according to a former senior intelligence official, it was agreed that, if limited strikes on Iran were carried out, the Administration could fend off criticism by arguing that they were a defensive action to save soldiers in Iraq. If Democrats objected, the Administration could say, “Bill Clinton did the same thing; he conducted limited strikes in Afghanistan, the Sudan, and in Baghdad to protect American lives.” The former intelligence official added, “There is a desperate effort by Cheney et al. to bring military action to Iran as soon as possible. Meanwhile, the politicians are saying, ‘You can’t do it, because every Republican is going to be defeated, and we’re only one fact from going over the cliff in Iraq.’ But Cheney doesn’t give a rat’s ass about the Republican worries, and neither does the President.”

Bryan Whitman, a Pentagon spokesman, said, “The President has made it clear that the United States government remains committed to a diplomatic solution with respect to Iran. The State Department is working diligently along with the international community to address our broad range of concerns.” (The White House declined to comment.)

I was repeatedly cautioned, in interviews, that the President has yet to issue the “execute order” that would be required for a military operation inside Iran, and such an order may never be issued. But there has been a significant increase in the tempo of attack planning. In mid-August, senior officials told reporters that the Administration intended to declare Iran’s Revolutionary Guard Corps a foreign terrorist organization. And two former senior officials of the C.I.A. told me that, by late summer, the agency had increased the size and the authority of the Iranian Operations Group. (A spokesman for the agency said, “The C.I.A. does not, as a rule, publicly discuss the relative size of its operational components.”)

“They’re moving everybody to the Iran desk,” one recently retired C.I.A. official said. “They’re dragging in a lot of analysts and ramping up everything. It’s just like the fall of 2002”—the months before the invasion of Iraq, when the Iraqi Operations Group became the most important in the agency. He added, “The guys now running the Iranian program have limited direct experience with Iran. In the event of an attack, how will the Iranians react? They will react, and the Administration has not thought it all the way through.”

That theme was echoed by Zbigniew Brzezinski, the former national-security adviser, who said that he had heard discussions of the White House’s more limited bombing plans for Iran. Brzezinski said that Iran would likely react to an American attack “by intensifying the conflict in Iraq and also in Afghanistan, their neighbors, and that could draw in Pakistan. We will be stuck in a regional war for twenty years.”

In a speech at the United Nations last week, Iran’s President, Mahmoud Ahmadinejad, was defiant. He referred to America as an “aggressor” state, and said, “How can the incompetents who cannot even manage and control themselves rule humanity and arrange its affairs? Unfortunately, they have put themselves in the position of God.” (The day before, at Columbia, he suggested that the facts of the Holocaust still needed to be determined.)

“A lot depends on how stupid the Iranians will be,” Brzezinski told me. “Will they cool off Ahmadinejad and tone down their language?” The Bush Administration, by charging that Iran was interfering in Iraq, was aiming “to paint it as ‘We’re responding to what is an intolerable situation,’ ” Brzezinski said. “This time, unlike the attack in Iraq, we’re going to play the victim. The name of our game seems to be to get the Iranians to overplay their hand.”

General David Petraeus, the commander of the multinational forces in Iraq, in his report to Congress in September, buttressed the Administration’s case against Iran. “None of us, earlier this year, appreciated the extent of Iranian involvement in Iraq, something about which we and Iraq’s leaders all now have greater concern,” he said. Iran, Petraeus said, was fighting “a proxy war against the Iraqi state and coalition forces in Iraq.”

Iran has had a presence in Iraq for decades; the extent and the purpose of its current activities there are in dispute, however. During Saddam Hussein’s rule, when the Sunni-dominated Baath Party brutally oppressed the majority Shiites, Iran supported them. Many in the present Iraqi Shiite leadership, including prominent members of the government of Prime Minister Nuri al-Maliki, spent years in exile in Iran; last week, at the Council on Foreign Relations, Maliki said, according to the Washington Post, that Iraq’s relations with the Iranians had “improved to the point that they are not interfering in our internal affairs.” Iran is so entrenched in Iraqi Shiite circles that any “proxy war” could be as much through the Iraqi state as against it. The crux of the Bush Administration’s strategic dilemma is that its decision to back a Shiite-led government after the fall of Saddam has empowered Iran, and made it impossible to exclude Iran from the Iraqi political scene.

Vali Nasr, a professor of international politics at Tufts University, who is an expert on Iran and Shiism, told me, “Between 2003 and 2006, the Iranians thought they were closest to the United States on the issue of Iraq.” The Iraqi Shia religious leadership encouraged Shiites to avoid confrontation with American soldiers and to participate in elections—believing that a one-man, one-vote election process could only result in a Shia-dominated government. Initially, the insurgency was mainly Sunni, especially Al Qaeda in Mesopotamia. Nasr told me that Iran’s policy since 2003 has been to provide funding, arms, and aid to several Shiite factions—including some in Maliki’s coalition. The problem, Nasr said, is that “once you put the arms on the ground you cannot control how they’re used later.”

In the Shiite view, the White House “only looks at Iran’s ties to Iraq in terms of security,” Nasr said. “Last year, over one million Iranians travelled to Iraq on pilgrimages, and there is more than a billion dollars a year in trading between the two countries. But the Americans act as if every Iranian inside Iraq were there to import weapons.”

Many of those who support the President’s policy argue that Iran poses an imminent threat. In a recent essay in Commentary, Norman Podhoretz depicted President Ahmadinejad as a revolutionary, “like Hitler . . . whose objective is to overturn the going international system and to replace it . . . with a new order dominated by Iran. . . . [T]he plain and brutal truth is that if Iran is to be prevented from developing a nuclear arsenal, there is no alternative to the actual use of military force.” Podhoretz concluded, “I pray with all my heart” that President Bush “will find it possible to take the only action that can stop Iran from following through on its evil intentions both toward us and toward Israel.” Podhoretz recently told politico.com that he had met with the President for about forty-five minutes to urge him to take military action against Iran, and believed that “Bush is going to hit” Iran before leaving office. (Podhoretz, one of the founders of neoconservatism, is a strong backer of Rudolph Giuliani’s Presidential campaign, and his son-in-law, Elliott Abrams, is a senior adviser to President Bush on national security.)

In early August, Army Lieutenant General Raymond Odierno, the second-ranking U.S. commander in Iraq, told the Times about an increase in attacks involving explosively formed penetrators, a type of lethal bomb that discharges a semi-molten copper slug that can rip through the armor of Humvees. The Times reported that U.S. intelligence and technical analyses indicated that Shiite militias had obtained the bombs from Iran. Odierno said that Iranians had been “surging support” over the past three or four months.

Questions remain, however, about the provenance of weapons in Iraq, especially given the rampant black market in arms. David Kay, a former C.I.A. adviser and the chief weapons inspector in Iraq for the United Nations, told me that his inspection team was astonished, in the aftermath of both Iraq wars, by “the huge amounts of arms” it found circulating among civilians and military personnel throughout the country. He recalled seeing stockpiles of explosively formed penetrators, as well as charges that had been recovered from unexploded American cluster bombs. Arms had also been supplied years ago by the Iranians to their Shiite allies in southern Iraq who had been persecuted by the Baath Party.

“I thought Petraeus went way beyond what Iran is doing inside Iraq today,” Kay said. “When the White House started its anti-Iran campaign, six months ago, I thought it was all craziness. Now it does look like there is some selective smuggling by Iran, but much of it has been in response to American pressure and American threats—more a ‘shot across the bow’ sort of thing, to let Washington know that it was not going to get away with its threats so freely. Iran is not giving the Iraqis the good stuff—the anti-aircraft missiles that can shoot down American planes and its advanced anti-tank weapons.”

Another element of the Administration’s case against Iran is the presence of Iranian agents in Iraq. General Petraeus, testifying before Congress, said that a commando faction of the Revolutionary Guards was seeking to turn its allies inside Iraq into a “Hezbollah-like force to serve its interests.” In August, Army Major General Rick Lynch, the commander of the 3rd Infantry Division, told reporters in Baghdad that his troops were tracking some fifty Iranian men sent by the Revolutionary Guards who were training Shiite insurgents south of Baghdad. “We know they’re here and we target them as well,” he said.

Patrick Clawson, an expert on Iran at the Washington Institute for Near East Policy, told me that “there are a lot of Iranians at any time inside Iraq, including those doing intelligence work and those doing humanitarian missions. It would be prudent for the Administration to produce more evidence of direct military training—or produce fighters captured in Iraq who had been trained in Iran.” He added, “It will be important for the Iraqi government to be able to state that they were unaware of this activity”; otherwise, given the intense relationship between the Iraqi Shiite leadership and Tehran, the Iranians could say that “they had been asked by the Iraqi government to train these people.” (In late August, American troops raided a Baghdad hotel and arrested a group of Iranians. They were a delegation from Iran’s energy ministry, and had been invited to Iraq by the Maliki government; they were later released.)

“If you want to attack, you have to prepare the groundwork, and you have to be prepared to show the evidence,” Clawson said. Adding to the complexity, he said, is a question that seems almost counterintuitive: “What is the attitude of Iraq going to be if we hit Iran? Such an attack could put a strain on the Iraqi government.”

A senior European diplomat, who works closely with American intelligence, told me that there is evidence that Iran has been making extensive preparation for an American bombing attack. “We know that the Iranians are strengthening their air-defense capabilities,” he said, “and we believe they will react asymmetrically—hitting targets in Europe and in Latin America.” There is also specific intelligence suggesting that Iran will be aided in these attacks by Hezbollah. “Hezbollah is capable, and they can do it,” the diplomat said.

In interviews with current and former officials, there were repeated complaints about the paucity of reliable information. A former high-level C.I.A. official said that the intelligence about who is doing what inside Iran “is so thin that nobody even wants his name on it. This is the problem.”

The difficulty of determining who is responsible for the chaos in Iraq can be seen in Basra, in the Shiite south, where British forces had earlier presided over a relatively secure area. Over the course of this year, however, the region became increasingly ungovernable, and by fall the British had retreated to fixed bases. A European official who has access to current intelligence told me that “there is a firm belief inside the American and U.K. intelligence community that Iran is supporting many of the groups in southern Iraq that are responsible for the deaths of British and American soldiers. Weapons and money are getting in from Iran. They have been able to penetrate many groups”—primarily the Mahdi Army and other Shiite militias.

A June, 2007, report by the International Crisis Group found, however, that Basra’s renewed instability was mainly the result of “the systematic abuse of official institutions, political assassinations, tribal vendettas, neighborhood vigilantism and enforcement of social mores, together with the rise of criminal mafias.” The report added that leading Iraqi politicians and officials “routinely invoke the threat of outside interference”—from bordering Iran—“to justify their behavior or evade responsibility for their failures.”

Earlier this year, before the surge in U.S. troops, the American command in Baghdad changed what had been a confrontational policy in western Iraq, the Sunni heartland (and the base of the Baathist regime), and began working with the Sunni tribes, including some tied to the insurgency. Tribal leaders are now getting combat support as well as money, intelligence, and arms, ostensibly to fight Al Qaeda in Mesopotamia. Empowering Sunni forces may undermine efforts toward national reconciliation, however. Already, tens of thousands of Shiites have fled Anbar Province, many to Shiite neighborhoods in Baghdad, while Sunnis have been forced from their homes in Shiite communities. Vali Nasr, of Tufts, called the internal displacement of communities in Iraq a form of “ethnic cleansing.”

“The American policy of supporting the Sunnis in western Iraq is making the Shia leadership very nervous,” Nasr said. “The White House makes it seem as if the Shia were afraid only of Al Qaeda—but they are afraid of the Sunni tribesmen we are arming. The Shia attitude is ‘So what if you’re getting rid of Al Qaeda?’ The problem of Sunni resistance is still there. The Americans believe they can distinguish between good and bad insurgents, but the Shia don’t share that distinction. For the Shia, they are all one adversary.”

Nasr went on, “The United States is trying to fight on all sides—Sunni and Shia—and be friends with all sides.” In the Shiite view, “It’s clear that the United States cannot bring security to Iraq, because it is not doing everything necessary to bring stability. If they did, they would talk to anybody to achieve it—even Iran and Syria,” Nasr said. (Such engagement was a major recommendation of the Iraq Study Group.) “America cannot bring stability in Iraq by fighting Iran in Iraq.”

The revised bombing plan for a possible attack, with its tightened focus on counterterrorism, is gathering support among generals and admirals in the Pentagon. The strategy calls for the use of sea-launched cruise missiles and more precisely targeted ground attacks and bombing strikes, including plans to destroy the most important Revolutionary Guard training camps, supply depots, and command and control facilities.

“Cheney’s option is now for a fast in and out—for surgical strikes,” the former senior American intelligence official told me. The Joint Chiefs have turned to the Navy, he said, which had been chafing over its role in the Air Force-dominated air war in Iraq. “The Navy’s planes, ships, and cruise missiles are in place in the Gulf and operating daily. They’ve got everything they need—even AWACS are in place and the targets in Iran have been programmed. The Navy is flying FA-18 missions every day in the Gulf.” There are also plans to hit Iran’s anti-aircraft surface-to-air missile sites. “We’ve got to get a path in and a path out,” the former official said.

A Pentagon consultant on counterterrorism told me that, if the bombing campaign took place, it would be accompanied by a series of what he called “short, sharp incursions” by American Special Forces units into suspected Iranian training sites. He said, “Cheney is devoted to this, no question.”

A limited bombing attack of this sort “only makes sense if the intelligence is good,” the consultant said. If the targets are not clearly defined, the bombing “will start as limited, but then there will be an ‘escalation special.’ Planners will say that we have to deal with Hezbollah here and Syria there. The goal will be to hit the cue ball one time and have all the balls go in the pocket. But add-ons are always there in strike planning.”

The surgical-strike plan has been shared with some of America’s allies, who have had mixed reactions to it. Israel’s military and political leaders were alarmed, believing, the consultant said, that it didn’t sufficiently target Iran’s nuclear facilities. The White House has been reassuring the Israeli government, the former senior official told me, that the more limited target list would still serve the goal of counter-proliferation by decapitating the leadership of the Revolutionary Guards, who are believed to have direct control over the nuclear-research program. “Our theory is that if we do the attacks as planned it will accomplish two things,” the former senior official said.

An Israeli official said, “Our main focus has been the Iranian nuclear facilities, not because other things aren’t important. We’ve worked on missile technology and terrorism, but we see the Iranian nuclear issue as one that cuts across everything.” Iran, he added, does not need to develop an actual warhead to be a threat. “Our problems begin when they learn and master the nuclear fuel cycle and when they have the nuclear materials,” he said. There was, for example, the possibility of a “dirty bomb,” or of Iran’s passing materials to terrorist groups. “There is still time for diplomacy to have an impact, but not a lot,” the Israeli official said. “We believe the technological timetable is moving faster than the diplomatic timetable. And if diplomacy doesn’t work, as they say, all options are on the table.”

The bombing plan has had its most positive reception from the newly elected government of Britain’s Prime Minister, Gordon Brown. A senior European official told me, “The British perception is that the Iranians are not making the progress they want to see in their nuclear-enrichment processing. All the intelligence community agree that Iran is providing critical assistance, training, and technology to a surprising number of terrorist groups in Iraq and Afghanistan, and, through Hezbollah, in Lebanon, and Israel/Palestine, too.”

There were four possible responses to this Iranian activity, the European official said: to do nothing (“There would be no retaliation to the Iranians for their attacks; this would be sending the wrong signal”); to publicize the Iranian actions (“There is one great difficulty with this option—the widespread lack of faith in American intelligence assessments”); to attack the Iranians operating inside Iraq (“We’ve been taking action since last December, and it does have an effect”); or, finally, to attack inside Iran.

The European official continued, “A major air strike against Iran could well lead to a rallying around the flag there, but a very careful targeting of terrorist training camps might not.” His view, he said, was that “once the Iranians get a bloody nose they rethink things.” For example, Ali Akbar Rafsanjani and Ali Larijani, two of Iran’s most influential political figures, “might go to the Supreme Leader and say, ‘The hard-line policies have got us into this mess. We must change our approach for the sake of the regime.’ ”

A retired American four-star general with close ties to the British military told me that there was another reason for Britain’s interest—shame over the failure of the Royal Navy to protect the sailors and Royal Marines who were seized by Iran on March 23rd, in the Persian Gulf. “The professional guys are saying that British honor is at stake, and if there’s another event like that in the water off Iran the British will hit back,” he said.

The revised bombing plan “could work—if it’s in response to an Iranian attack,” the retired four-star general said. “The British may want to do it to get even, but the more reasonable people are saying, ‘Let’s do it if the Iranians stage a cross-border attack inside Iraq.’ It’s got to be ten dead American soldiers and four burned trucks.” There is, he added, “a widespread belief in London that Tony Blair’s government was sold a bill of goods by the White House in the buildup to the war against Iraq. So if somebody comes into Gordon Brown’s office and says, ‘We have this intelligence from America,’ Brown will ask, ‘Where did it come from? Have we verified it?’ The burden of proof is high.”

The French government shares the Administration’s sense of urgency about Iran’s nuclear program, and believes that Iran will be able to produce a warhead within two years. France’s newly elected President, Nicolas Sarkozy, created a stir in late August when he warned that Iran could be attacked if it did not halt is nuclear program. Nonetheless, France has indicated to the White House that it has doubts about a limited strike, the former senior intelligence official told me. Many in the French government have concluded that the Bush Administration has exaggerated the extent of Iranian meddling inside Iraq; they believe, according to a European diplomat, that “the American problems in Iraq are due to their own mistakes, and now the Americans are trying to show some teeth. An American bombing will show only that the Bush Administration has its own agenda toward Iran.”

A European intelligence official made a similar point. “If you attack Iran,” he told me, “and do not label it as being against Iran’s nuclear facilities, it will strengthen the regime, and help to make the Islamic air in the Middle East thicker.”

Ahmadinejad, in his speech at the United Nations, said that Iran considered the dispute over its nuclear program “closed.” Iran would deal with it only through the International Atomic Energy Agency, he said, and had decided to “disregard unlawful and political impositions of the arrogant powers.” He added, in a press conference after the speech, “the decisions of the United States and France are not important.”

The director general of the I.A.E.A., Mohamed ElBaradei, has for years been in an often bitter public dispute with the Bush Administration; the agency’s most recent report found that Iran was far less proficient in enriching uranium than expected. A diplomat in Vienna, where the I.A.E.A. is based, said, “The Iranians are years away from making a bomb, as ElBaradei has said all along. Running three thousand centrifuges does not make a bomb.” The diplomat added, referring to hawks in the Bush Administration, “They don’t like ElBaradei, because they are in a state of denial. And now their negotiating policy has failed, and Iran is still enriching uranium and still making progress.”

The diplomat expressed the bitterness that has marked the I.A.E.A.’s dealings with the Bush Administration since the buildup to the 2003 invasion of Iraq. “The White House’s claims were all a pack of lies, and Mohamed is dismissive of those lies,” the diplomat said.

Hans Blix, a former head of the I.A.E.A., questioned the Bush Administration’s commitment to diplomacy. “There are important cards that Washington could play; instead, they have three aircraft carriers sitting in the Persian Gulf,” he said. Speaking of Iran’s role in Iraq, Blix added, “My impression is that the United States has been trying to push up the accusations against Iran as a basis for a possible attack—as an excuse for jumping on them.”

The Iranian leadership is feeling the pressure. In the press conference after his U.N. speech, Ahmadinejad was asked about a possible attack. “They want to hurt us,” he said, “but, with the will of God, they won’t be able to do it.” According to a former State Department adviser on Iran, the Iranians complained, in diplomatic meetings in Baghdad with Ambassador Crocker, about a refusal by the Bush Administration to take advantage of their knowledge of the Iraqi political scene. The former adviser said, “They’ve been trying to convey to the United States that ‘We can help you in Iraq. Nobody knows Iraq better than us.’ ” Instead, the Iranians are preparing for an American attack.

The adviser said that he had heard from a source in Iran that the Revolutionary Guards have been telling religious leaders that they can stand up to an American attack. “The Guards are claiming that they can infiltrate American security,” the adviser said. “They are bragging that they have spray-painted an American warship—to signal the Americans that they can get close to them.” (I was told by the former senior intelligence official that there was an unexplained incident, this spring, in which an American warship was spray-painted with a bull’s-eye while docked in Qatar, which may have been the source of the boasts.)

“Do you think those crazies in Tehran are going to say, ‘Uncle Sam is here! We’d better stand down’? ” the former senior intelligence official said. “The reality is an attack will make things ten times warmer.”

Another recent incident, in Afghanistan, reflects the tension over intelligence. In July, the London Telegraph reported that what appeared to be an SA-7 shoulder-launched missile was fired at an American C-130 Hercules aircraft. The missile missed its mark. Months earlier, British commandos had intercepted a few truckloads of weapons, including one containing a working SA-7 missile, coming across the Iranian border. But there was no way of determining whether the missile fired at the C-130 had come from Iran—especially since SA-7s are available through black-market arms dealers.

Vincent Cannistraro, a retired C.I.A. officer who has worked closely with his counterparts in Britain, added to the story: “The Brits told me that they were afraid at first to tell us about the incident—in fear that Cheney would use it as a reason to attack Iran.” The intelligence subsequently was forwarded, he said.

The retired four-star general confirmed that British intelligence “was worried” about passing the information along. “The Brits don’t trust the Iranians,” the retired general said, “but they also don’t trust Bush and Cheney.”