The Bush Administration, while publicly advocating diplomacy in order to stop Iran from pursuing a nuclear weapon, has increased clandestine activities inside Iran and intensified planning for a possible major air attack. Current and former American military and intelligence officials said that Air Force planning groups are drawing up lists of targets, and teams of American combat troops have been ordered into Iran, under cover, to collect targeting data and to establish contact with anti-government ethnic-minority groups. The officials say that President Bush is determined to deny the Iranian regime the opportunity to begin a pilot program, planned for this spring, to enrich uranium.

American and European intelligence agencies, and the International Atomic Energy Agency (I.A.E.A.), agree that Iran is intent on developing the capability to produce nuclear weapons. But there are widely differing estimates of how long that will take, and whether diplomacy, sanctions, or military action is the best way to prevent it. Iran insists that its research is for peaceful use only, in keeping with the Nuclear Non-Proliferation Treaty, and that it will not be delayed or deterred.

There is a growing conviction among members of the United States military, and in the international community, that President Bush’s ultimate goal in the nuclear confrontation with Iran is regime change. Iran’s President, Mahmoud Ahmadinejad, has challenged the reality of the Holocaust and said that Israel must be “wiped off the map.” Bush and others in the White House view him as a potential Adolf Hitler, a former senior intelligence official said. “That’s the name they’re using. They say, ‘Will Iran get a strategic weapon and threaten another world war?’ ”

A government consultant with close ties to the civilian leadership in the Pentagon said that Bush was “absolutely convinced that Iran is going to get the bomb” if it is not stopped. He said that the President believes that he must do “what no Democrat or Republican, if elected in the future, would have the courage to do,” and “that saving Iran is going to be his legacy.”

One former defense official, who still deals with sensitive issues for the Bush Administration, told me that the military planning was premised on a belief that “a sustained bombing campaign in Iran will humiliate the religious leadership and lead the public to rise up and overthrow the government.” He added, “I was shocked when I heard it, and asked myself, ‘What are they smoking?’ ”

The rationale for regime change was articulated in early March by Patrick Clawson, an Iran expert who is the deputy director for research at the Washington Institute for Near East Policy and who has been a supporter of President Bush. “So long as Iran has an Islamic republic, it will have a nuclear-weapons program, at least clandestinely,” Clawson told the Senate Foreign Relations Committee on March 2nd. “The key issue, therefore, is: How long will the present Iranian regime last?”

When I spoke to Clawson, he emphasized that “this Administration is putting a lot of effort into diplomacy.” However, he added, Iran had no choice other than to accede to America’s demands or face a military attack. Clawson said that he fears that Ahmadinejad “sees the West as wimps and thinks we will eventually cave in. We have to be ready to deal with Iran if the crisis escalates.” Clawson said that he would prefer to rely on sabotage and other clandestine activities, such as “industrial accidents.” But, he said, it would be prudent to prepare for a wider war, “given the way the Iranians are acting. This is not like planning to invade Quebec.”

One military planner told me that White House criticisms of Iran and the high tempo of planning and clandestine activities amount to a campaign of “coercion” aimed at Iran. “You have to be ready to go, and we’ll see how they respond,” the officer said. “You have to really show a threat in order to get Ahmadinejad to back down.” He added, “People think Bush has been focussed on Saddam Hussein since 9/11,” but, “in my view, if you had to name one nation that was his focus all the way along, it was Iran.” (In response to detailed requests for comment, the White House said that it would not comment on military planning but added, “As the President has indicated, we are pursuing a diplomatic solution”; the Defense Department also said that Iran was being dealt with through “diplomatic channels” but wouldn’t elaborate on that; the C.I.A. said that there were “inaccuracies” in this account but would not specify them.)

“This is much more than a nuclear issue,” one high-ranking diplomat told me in Vienna. “That’s just a rallying point, and there is still time to fix it. But the Administration believes it cannot be fixed unless they control the hearts and minds of Iran. The real issue is who is going to control the Middle East and its oil in the next ten years.”

A senior Pentagon adviser on the war on terror expressed a similar view. “This White House believes that the only way to solve the problem is to change the power structure in Iran, and that means war,” he said. The danger, he said, was that “it also reinforces the belief inside Iran that the only way to defend the country is to have a nuclear capability.” A military conflict that destabilized the region could also increase the risk of terror: “Hezbollah comes into play,” the adviser said, referring to the terror group that is considered one of the world’s most successful, and which is now a Lebanese political party with strong ties to Iran. “And here comes Al Qaeda.”

In recent weeks, the President has quietly initiated a series of talks on plans for Iran with a few key senators and members of Congress, including at least one Democrat. A senior member of the House Appropriations Committee, who did not take part in the meetings but has discussed their content with his colleagues, told me that there had been “no formal briefings,” because “they’re reluctant to brief the minority. They’re doing the Senate, somewhat selectively.”

The House member said that no one in the meetings “is really objecting” to the talk of war. “The people they’re briefing are the same ones who led the charge on Iraq. At most, questions are raised: How are you going to hit all the sites at once? How are you going to get deep enough?” (Iran is building facilities underground.) “There’s no pressure from Congress” not to take military action, the House member added. “The only political pressure is from the guys who want to do it.” Speaking of President Bush, the House member said, “The most worrisome thing is that this guy has a messianic vision.”

Some operations, apparently aimed in part at intimidating Iran, are already under way. American Naval tactical aircraft, operating from carriers in the Arabian Sea, have been flying simulated nuclear-weapons delivery missions—rapid ascending maneuvers known as “over the shoulder” bombing—since last summer, the former official said, within range of Iranian coastal radars.

Last month, in a paper given at a conference on Middle East security in Berlin, Colonel Sam Gardiner, a military analyst who taught at the National War College before retiring from the Air Force, in 1987, provided an estimate of what would be needed to destroy Iran’s nuclear program. Working from satellite photographs of the known facilities, Gardiner estimated that at least four hundred targets would have to be hit. He added:

I don’t think a U.S. military planner would want to stop there. Iran probably has two chemical-production plants. We would hit those. We would want to hit the medium-range ballistic missiles that have just recently been moved closer to Iraq. There are fourteen airfields with sheltered aircraft. . . . We’d want to get rid of that threat. We would want to hit the assets that could be used to threaten Gulf shipping. That means targeting the cruise-missile sites and the Iranian diesel submarines. . . . Some of the facilities may be too difficult to target even with penetrating weapons. The U.S. will have to use Special Operations units.

One of the military’s initial option plans, as presented to the White House by the Pentagon this winter, calls for the use of a bunker-buster tactical nuclear weapon, such as the B61-11, against underground nuclear sites. One target is Iran’s main centrifuge plant, at Natanz, nearly two hundred miles south of Tehran. Natanz, which is no longer under I.A.E.A. safeguards, reportedly has underground floor space to hold fifty thousand centrifuges, and laboratories and workspaces buried approximately seventy-five feet beneath the surface. That number of centrifuges could provide enough enriched uranium for about twenty nuclear warheads a year. (Iran has acknowledged that it initially kept the existence of its enrichment program hidden from I.A.E.A. inspectors, but claims that none of its current activity is barred by the Non-Proliferation Treaty.) The elimination of Natanz would be a major setback for Iran’s nuclear ambitions, but the conventional weapons in the American arsenal could not insure the destruction of facilities under seventy-five feet of earth and rock, especially if they are reinforced with concrete.

There is a Cold War precedent for targeting deep underground bunkers with nuclear weapons. In the early nineteen-eighties, the American intelligence community watched as the Soviet government began digging a huge underground complex outside Moscow. Analysts concluded that the underground facility was designed for “continuity of government”—for the political and military leadership to survive a nuclear war. (There are similar facilities, in Virginia and Pennsylvania, for the American leadership.) The Soviet facility still exists, and much of what the U.S. knows about it remains classified. “The ‘tell’ ”—the giveaway—“was the ventilator shafts, some of which were disguised,” the former senior intelligence official told me. At the time, he said, it was determined that “only nukes” could destroy the bunker. He added that some American intelligence analysts believe that the Russians helped the Iranians design their underground facility. “We see a similarity of design,” specifically in the ventilator shafts, he said.

A former high-level Defense Department official told me that, in his view, even limited bombing would allow the U.S. to “go in there and do enough damage to slow down the nuclear infrastructure—it’s feasible.” The former defense official said, “The Iranians don’t have friends, and we can tell them that, if necessary, we’ll keep knocking back their infrastructure. The United States should act like we’re ready to go.” He added, “We don’t have to knock down all of their air defenses. Our stealth bombers and standoff missiles really work, and we can blow fixed things up. We can do things on the ground, too, but it’s difficult and very dangerous—put bad stuff in ventilator shafts and put them to sleep.”

But those who are familiar with the Soviet bunker, according to the former senior intelligence official, “say ‘No way.’ You’ve got to know what’s underneath—to know which ventilator feeds people, or diesel generators, or which are false. And there’s a lot that we don’t know.” The lack of reliable intelligence leaves military planners, given the goal of totally destroying the sites, little choice but to consider the use of tactical nuclear weapons. “Every other option, in the view of the nuclear weaponeers, would leave a gap,” the former senior intelligence official said. “ ‘Decisive’ is the key word of the Air Force’s planning. It’s a tough decision. But we made it in Japan.”

He went on, “Nuclear planners go through extensive training and learn the technical details of damage and fallout—we’re talking about mushroom clouds, radiation, mass casualties, and contamination over years. This is not an underground nuclear test, where all you see is the earth raised a little bit. These politicians don’t have a clue, and whenever anybody tries to get it out”—remove the nuclear option—“they’re shouted down.”

The attention given to the nuclear option has created serious misgivings inside the offices of the Joint Chiefs of Staff, he added, and some officers have talked about resigning. Late this winter, the Joint Chiefs of Staff sought to remove the nuclear option from the evolving war plans for Iran—without success, the former intelligence official said. “The White House said, ‘Why are you challenging this? The option came from you.’ ”

The Pentagon adviser on the war on terror confirmed that some in the Administration were looking seriously at this option, which he linked to a resurgence of interest in tactical nuclear weapons among Pentagon civilians and in policy circles. He called it “a juggernaut that has to be stopped.” He also confirmed that some senior officers and officials were considering resigning over the issue. “There are very strong sentiments within the military against brandishing nuclear weapons against other countries,” the adviser told me. “This goes to high levels.” The matter may soon reach a decisive point, he said, because the Joint Chiefs had agreed to give President Bush a formal recommendation stating that they are strongly opposed to considering the nuclear option for Iran. “The internal debate on this has hardened in recent weeks,” the adviser said. “And, if senior Pentagon officers express their opposition to the use of offensive nuclear weapons, then it will never happen.”

The adviser added, however, that the idea of using tactical nuclear weapons in such situations has gained support from the Defense Science Board, an advisory panel whose members are selected by Secretary of Defense Donald Rumsfeld. “They’re telling the Pentagon that we can build the B61 with more blast and less radiation,” he said.

The chairman of the Defense Science Board is William Schneider, Jr., an Under-Secretary of State in the Reagan Administration. In January, 2001, as President Bush prepared to take office, Schneider served on an ad-hoc panel on nuclear forces sponsored by the National Institute for Public Policy, a conservative think tank. The panel’s report recommended treating tactical nuclear weapons as an essential part of the U.S. arsenal and noted their suitability “for those occasions when the certain and prompt destruction of high priority targets is essential and beyond the promise of conventional weapons.” Several signers of the report are now prominent members of the Bush Administration, including Stephen Hadley, the national-security adviser; Stephen Cambone, the Under-Secretary of Defense for Intelligence; and Robert Joseph, the Under-Secretary of State for Arms Control and International Security.

The Pentagon adviser questioned the value of air strikes. “The Iranians have distributed their nuclear activity very well, and we have no clue where some of the key stuff is. It could even be out of the country,” he said. He warned, as did many others, that bombing Iran could provoke “a chain reaction” of attacks on American facilities and citizens throughout the world: “What will 1.2 billion Muslims think the day we attack Iran?”

With or without the nuclear option, the list of targets may inevitably expand. One recently retired high-level Bush Administration official, who is also an expert on war planning, told me that he would have vigorously argued against an air attack on Iran, because “Iran is a much tougher target” than Iraq. But, he added, “If you’re going to do any bombing to stop the nukes, you might as well improve your lie across the board. Maybe hit some training camps, and clear up a lot of other problems.”

The Pentagon adviser said that, in the event of an attack, the Air Force intended to strike many hundreds of targets in Iran but that “ninety-nine per cent of them have nothing to do with proliferation. There are people who believe it’s the way to operate”—that the Administration can achieve its policy goals in Iran with a bombing campaign, an idea that has been supported by neoconservatives.

If the order were to be given for an attack, the American combat troops now operating in Iran would be in position to mark the critical targets with laser beams, to insure bombing accuracy and to minimize civilian casualties. As of early winter, I was told by the government consultant with close ties to civilians in the Pentagon, the units were also working with minority groups in Iran, including the Azeris, in the north, the Baluchis, in the southeast, and the Kurds, in the northeast. The troops “are studying the terrain, and giving away walking-around money to ethnic tribes, and recruiting scouts from local tribes and shepherds,” the consultant said. One goal is to get “eyes on the ground”—quoting a line from “Othello,” he said, “Give me the ocular proof.” The broader aim, the consultant said, is to “encourage ethnic tensions” and undermine the regime.

The new mission for the combat troops is a product of Defense Secretary Rumsfeld’s long-standing interest in expanding the role of the military in covert operations, which was made official policy in the Pentagon’s Quadrennial Defense Review, published in February. Such activities, if conducted by C.I.A. operatives, would need a Presidential Finding and would have to be reported to key members of Congress.

“ ‘Force protection’ is the new buzzword,” the former senior intelligence official told me. He was referring to the Pentagon’s position that clandestine activities that can be broadly classified as preparing the battlefield or protecting troops are military, not intelligence, operations, and are therefore not subject to congressional oversight. “The guys in the Joint Chiefs of Staff say there are a lot of uncertainties in Iran,” he said. “We need to have more than what we had in Iraq. Now we have the green light to do everything we want.”

The President’s deep distrust of Ahmadinejad has strengthened his determination to confront Iran. This view has been reinforced by allegations that Ahmadinejad, who joined a special-forces brigade of the Revolutionary Guards in 1986, may have been involved in terrorist activities in the late eighties. (There are gaps in Ahmadinejad’s official biography in this period.) Ahmadinejad has reportedly been connected to Imad Mughniyeh, a terrorist who has been implicated in the deadly bombings of the U.S. Embassy and the U.S. Marine barracks in Beirut, in 1983. Mughniyeh was then the security chief of Hezbollah; he remains on the F.B.I.’s list of most-wanted terrorists.

Robert Baer, who was a C.I.A. officer in the Middle East and elsewhere for two decades, told me that Ahmadinejad and his Revolutionary Guard colleagues in the Iranian government “are capable of making a bomb, hiding it, and launching it at Israel. They’re apocalyptic Shiites. If you’re sitting in Tel Aviv and you believe they’ve got nukes and missiles—you’ve got to take them out. These guys are nuts, and there’s no reason to back off.”

Under Ahmadinejad, the Revolutionary Guards have expanded their power base throughout the Iranian bureaucracy; by the end of January, they had replaced thousands of civil servants with their own members. One former senior United Nations official, who has extensive experience with Iran, depicted the turnover as “a white coup,” with ominous implications for the West. “Professionals in the Foreign Ministry are out; others are waiting to be kicked out,” he said. “We may be too late. These guys now believe that they are stronger than ever since the revolution.” He said that, particularly in consideration of China’s emergence as a superpower, Iran’s attitude was “To hell with the West. You can do as much as you like.”

Iran’s supreme religious leader, Ayatollah Khamenei, is considered by many experts to be in a stronger position than Ahmadinejad. “Ahmadinejad is not in control,” one European diplomat told me. “Power is diffuse in Iran. The Revolutionary Guards are among the key backers of the nuclear program, but, ultimately, I don’t think they are in charge of it. The Supreme Leader has the casting vote on the nuclear program, and the Guards will not take action without his approval.”

The Pentagon adviser on the war on terror said that “allowing Iran to have the bomb is not on the table. We cannot have nukes being sent downstream to a terror network. It’s just too dangerous.” He added, “The whole internal debate is on which way to go”—in terms of stopping the Iranian program. It is possible, the adviser said, that Iran will unilaterally renounce its nuclear plans—and forestall the American action. “God may smile on us, but I don’t think so. The bottom line is that Iran cannot become a nuclear-weapons state. The problem is that the Iranians realize that only by becoming a nuclear state can they defend themselves against the U.S. Something bad is going to happen.”

While almost no one disputes Iran’s nuclear ambitions, there is intense debate over how soon it could get the bomb, and what to do about that. Robert Gallucci, a former government expert on nonproliferation who is now the dean of the School of Foreign Service at Georgetown, told me, “Based on what I know, Iran could be eight to ten years away” from developing a deliverable nuclear weapon. Gallucci added, “If they had a covert nuclear program and we could prove it, and we could not stop it by negotiation, diplomacy, or the threat of sanctions, I’d be in favor of taking it out. But if you do it”—bomb Iran—“without being able to show there’s a secret program, you’re in trouble.”

Meir Dagan, the head of Mossad, Israel’s intelligence agency, told the Knesset last December that “Iran is one to two years away, at the latest, from having enriched uranium. From that point, the completion of their nuclear weapon is simply a technical matter.” In a conversation with me, a senior Israeli intelligence official talked about what he said was Iran’s duplicity: “There are two parallel nuclear programs” inside Iran—the program declared to the I.A.E.A. and a separate operation, run by the military and the Revolutionary Guards. Israeli officials have repeatedly made this argument, but Israel has not produced public evidence to support it. Richard Armitage, the Deputy Secretary of State in Bush’s first term, told me, “I think Iran has a secret nuclear-weapons program—I believe it, but I don’t know it.”

In recent months, the Pakistani government has given the U.S. new access to A. Q. Khan, the so-called father of the Pakistani atomic bomb. Khan, who is now living under house arrest in Islamabad, is accused of setting up a black market in nuclear materials; he made at least one clandestine visit to Tehran in the late nineteen-eighties. In the most recent interrogations, Khan has provided information on Iran’s weapons design and its time line for building a bomb. “The picture is of ‘unquestionable danger,’ ” the former senior intelligence official said. (The Pentagon adviser also confirmed that Khan has been “singing like a canary.”) The concern, the former senior official said, is that “Khan has credibility problems. He is suggestible, and he’s telling the neoconservatives what they want to hear”—or what might be useful to Pakistan’s President, Pervez Musharraf, who is under pressure to assist Washington in the war on terror.

“I think Khan’s leading us on,” the former intelligence official said. “I don’t know anybody who says, ‘Here’s the smoking gun.’ But lights are beginning to blink. He’s feeding us information on the time line, and targeting information is coming in from our own sources— sensors and the covert teams. The C.I.A., which was so burned by Iraqi W.M.D., is going to the Pentagon and the Vice-President’s office saying, ‘It’s all new stuff.’ People in the Administration are saying, ‘We’ve got enough.’ ”

The Administration’s case against Iran is compromised by its history of promoting false intelligence on Iraq’s weapons of mass destruction. In a recent essay on the Foreign Policy Web site, entitled “Fool Me Twice,” Joseph Cirincione, the director for nonproliferation at the Carnegie Endowment for International Peace, wrote, “The unfolding administration strategy appears to be an effort to repeat its successful campaign for the Iraq war.” He noted several parallels:

The vice president of the United States gives a major speech focused on the threat from an oil-rich nation in the Middle East. The U.S. Secretary of State tells Congress that the same nation is our most serious global challenge. The Secretary of Defense calls that nation the leading supporter of global terrorism.

Cirincione called some of the Administration’s claims about Iran “questionable” or lacking in evidence. When I spoke to him, he asked, “What do we know? What is the threat? The question is: How urgent is all this?” The answer, he said, “is in the intelligence community and the I.A.E.A.” (In August, the Washington Post reported that the most recent comprehensive National Intelligence Estimate predicted that Iran was a decade away from being a nuclear power.)

Last year, the Bush Administration briefed I.A.E.A. officials on what it said was new and alarming information about Iran’s weapons program which had been retrieved from an Iranian’s laptop. The new data included more than a thousand pages of technical drawings of weapons systems. The Washington Post reported that there were also designs for a small facility that could be used in the uranium-enrichment process. Leaks about the laptop became the focal point of stories in the Times and elsewhere. The stories were generally careful to note that the materials could have been fabricated, but also quoted senior American officials as saying that they appeared to be legitimate. The headline in the Times’ account read, “RELYING ON COMPUTER, U.S. SEEKS TO PROVE IRAN’S NUCLEAR AIMS.”

I was told in interviews with American and European intelligence officials, however, that the laptop was more suspect and less revelatory than it had been depicted. The Iranian who owned the laptop had initially been recruited by German and American intelligence operatives, working together. The Americans eventually lost interest in him. The Germans kept on, but the Iranian was seized by the Iranian counter-intelligence force. It is not known where he is today. Some family members managed to leave Iran with his laptop and handed it over at a U.S. embassy, apparently in Europe. It was a classic “walk-in.”

A European intelligence official said, “There was some hesitation on our side” about what the materials really proved, “and we are still not convinced.” The drawings were not meticulous, as newspaper accounts suggested, “but had the character of sketches,” the European official said. “It was not a slam-dunk smoking gun.”

The threat of American military action has created dismay at the headquarters of the I.A.E.A., in Vienna. The agency’s officials believe that Iran wants to be able to make a nuclear weapon, but “nobody has presented an inch of evidence of a parallel nuclear-weapons program in Iran,” the high-ranking diplomat told me. The I.A.E.A.’s best estimate is that the Iranians are five years away from building a nuclear bomb. “But, if the United States does anything militarily, they will make the development of a bomb a matter of Iranian national pride,” the diplomat said. “The whole issue is America’s risk assessment of Iran’s future intentions, and they don’t trust the regime. Iran is a menace to American policy.”

In Vienna, I was told of an exceedingly testy meeting earlier this year between Mohamed ElBaradei, the I.A.E.A.’s director-general, who won the Nobel Peace Prize last year, and Robert Joseph, the Under-Secretary of State for Arms Control. Joseph’s message was blunt, one diplomat recalled: “We cannot have a single centrifuge spinning in Iran. Iran is a direct threat to the national security of the United States and our allies, and we will not tolerate it. We want you to give us an understanding that you will not say anything publicly that will undermine us. ”

Joseph’s heavy-handedness was unnecessary, the diplomat said, since the I.A.E.A. already had been inclined to take a hard stand against Iran. “All of the inspectors are angry at being misled by the Iranians, and some think the Iranian leadership are nutcases—one hundred per cent totally certified nuts,” the diplomat said. He added that ElBaradei’s overriding concern is that the Iranian leaders “want confrontation, just like the neocons on the other side”—in Washington. “At the end of the day, it will work only if the United States agrees to talk to the Iranians.”

The central question—whether Iran will be able to proceed with its plans to enrich uranium—is now before the United Nations, with the Russians and the Chinese reluctant to impose sanctions on Tehran. A discouraged former I.A.E.A. official told me in late March that, at this point, “there’s nothing the Iranians could do that would result in a positive outcome. American diplomacy does not allow for it. Even if they announce a stoppage of enrichment, nobody will believe them. It’s a dead end.”

Another diplomat in Vienna asked me, “Why would the West take the risk of going to war against that kind of target without giving it to the I.A.E.A. to verify? We’re low-cost, and we can create a program that will force Iran to put its cards on the table.” A Western Ambassador in Vienna expressed similar distress at the White House’s dismissal of the I.A.E.A. He said, “If you don’t believe that the I.A.E.A. can establish an inspection system—if you don’t trust them—you can only bomb.”

There is little sympathy for the I.A.E.A. in the Bush Administration or among its European allies. “We’re quite frustrated with the director-general,” the European diplomat told me. “His basic approach has been to describe this as a dispute between two sides with equal weight. It’s not. We’re the good guys! ElBaradei has been pushing the idea of letting Iran have a small nuclear-enrichment program, which is ludicrous. It’s not his job to push ideas that pose a serious proliferation risk.”

The Europeans are rattled, however, by their growing perception that President Bush and Vice-President Dick Cheney believe a bombing campaign will be needed, and that their real goal is regime change. “Everyone is on the same page about the Iranian bomb, but the United States wants regime change,” a European diplomatic adviser told me. He added, “The Europeans have a role to play as long as they don’t have to choose between going along with the Russians and the Chinese or going along with Washington on something they don’t want. Their policy is to keep the Americans engaged in something the Europeans can live with. It may be untenable.”

“The Brits think this is a very bad idea,” Flynt Leverett, a former National Security Council staff member who is now a senior fellow at the Brookings Institution’s Saban Center, told me, “but they’re really worried we’re going to do it.” The European diplomatic adviser acknowledged that the British Foreign Office was aware of war planning in Washington but that, “short of a smoking gun, it’s going to be very difficult to line up the Europeans on Iran.” He said that the British “are jumpy about the Americans going full bore on the Iranians, with no compromise.”

The European diplomat said that he was skeptical that Iran, given its record, had admitted to everything it was doing, but “to the best of our knowledge the Iranian capability is not at the point where they could successfully run centrifuges” to enrich uranium in quantity. One reason for pursuing diplomacy was, he said, Iran’s essential pragmatism. “The regime acts in its best interests,” he said. Iran’s leaders “take a hard-line approach on the nuclear issue and they want to call the American bluff,” believing that “the tougher they are the more likely the West will fold.” But, he said, “From what we’ve seen with Iran, they will appear superconfident until the moment they back off.”

The diplomat went on, “You never reward bad behavior, and this is not the time to offer concessions. We need to find ways to impose sufficient costs to bring the regime to its senses. It’s going to be a close call, but I think if there is unity in opposition and the price imposed”—in sanctions—“is sufficient, they may back down. It’s too early to give up on the U.N. route.” He added, “If the diplomatic process doesn’t work, there is no military ‘solution.’ There may be a military option, but the impact could be catastrophic.”

Tony Blair, the British Prime Minister, was George Bush’s most dependable ally in the year leading up to the 2003 invasion of Iraq. But he and his party have been racked by a series of financial scandals, and his popularity is at a low point. Jack Straw, the Foreign Secretary, said last year that military action against Iran was “inconceivable.” Blair has been more circumspect, saying publicly that one should never take options off the table.

Other European officials expressed similar skepticism about the value of an American bombing campaign. “The Iranian economy is in bad shape, and Ahmadinejad is in bad shape politically,” the European intelligence official told me. “He will benefit politically from American bombing. You can do it, but the results will be worse.” An American attack, he said, would alienate ordinary Iranians, including those who might be sympathetic to the U.S. “Iran is no longer living in the Stone Age, and the young people there have access to U.S. movies and books, and they love it,” he said. “If there was a charm offensive with Iran, the mullahs would be in trouble in the long run.”

Another European official told me that he was aware that many in Washington wanted action. “It’s always the same guys,” he said, with a resigned shrug. “There is a belief that diplomacy is doomed to fail. The timetable is short.”

A key ally with an important voice in the debate is Israel, whose leadership has warned for years that it viewed any attempt by Iran to begin enriching uranium as a point of no return. I was told by several officials that the White House’s interest in preventing an Israeli attack on a Muslim country, which would provoke a backlash across the region, was a factor in its decision to begin the current operational planning. In a speech in Cleveland on March 20th, President Bush depicted Ahmadinejad’s hostility toward Israel as a “serious threat. It’s a threat to world peace.” He added, “I made it clear, I’ll make it clear again, that we will use military might to protect our ally Israel.”

Any American bombing attack, Richard Armitage told me, would have to consider the following questions: “What will happen in the other Islamic countries? What ability does Iran have to reach us and touch us globally—that is, terrorism? Will Syria and Lebanon up the pressure on Israel? What does the attack do to our already diminished international standing? And what does this mean for Russia, China, and the U.N. Security Council?”

Iran, which now produces nearly four million barrels of oil a day, would not have to cut off production to disrupt the world’s oil markets. It could blockade or mine the Strait of Hormuz, the thirty-four-mile-wide passage through which Middle Eastern oil reaches the Indian Ocean. Nonetheless, the recently retired defense official dismissed the strategic consequences of such actions. He told me that the U.S. Navy could keep shipping open by conducting salvage missions and putting mine- sweepers to work. “It’s impossible to block passage,” he said. The government consultant with ties to the Pentagon also said he believed that the oil problem could be managed, pointing out that the U.S. has enough in its strategic reserves to keep America running for sixty days. However, those in the oil business I spoke to were less optimistic; one industry expert estimated that the price per barrel would immediately spike, to anywhere from ninety to a hundred dollars per barrel, and could go higher, depending on the duration and scope of the conflict.

Michel Samaha, a veteran Lebanese Christian politician and former cabinet minister in Beirut, told me that the Iranian retaliation might be focussed on exposed oil and gas fields in Saudi Arabia, Qatar, Kuwait, and the United Arab Emirates. “They would be at risk,” he said, “and this could begin the real jihad of Iran versus the West. You will have a messy world.”

Iran could also initiate a wave of terror attacks in Iraq and elsewhere, with the help of Hezbollah. On April 2nd, the Washington Post reported that the planning to counter such attacks “is consuming a lot of time” at U.S. intelligence agencies. “The best terror network in the world has remained neutral in the terror war for the past several years,” the Pentagon adviser on the war on terror said of Hezbollah. “This will mobilize them and put us up against the group that drove Israel out of southern Lebanon. If we move against Iran, Hezbollah will not sit on the sidelines. Unless the Israelis take them out, they will mobilize against us.” (When I asked the government consultant about that possibility, he said that, if Hezbollah fired rockets into northern Israel, “Israel and the new Lebanese government will finish them off.”)

The adviser went on, “If we go, the southern half of Iraq will light up like a candle.” The American, British, and other coalition forces in Iraq would be at greater risk of attack from Iranian troops or from Shiite militias operating on instructions from Iran. (Iran, which is predominantly Shiite, has close ties to the leading Shiite parties in Iraq.) A retired four-star general told me that, despite the eight thousand British troops in the region, “the Iranians could take Basra with ten mullahs and one sound truck.”

“If you attack,” the high-ranking diplomat told me in Vienna, “Ahmadinejad will be the new Saddam Hussein of the Arab world, but with more credibility and more power. You must bite the bullet and sit down with the Iranians.”

The diplomat went on, “There are people in Washington who would be unhappy if we found a solution. They are still banking on isolation and regime change. This is wishful thinking.” He added, “The window of opportunity is now.”