Five years with President Bush show that his administration's boldest assertions are often, in fact, statements of serious intent - whether they're about "regime change" in Iraq or educational standards for children.
Mr. Bush has laid down another such marker with his insistence that he will not allow Iran to have nuclear-weapons capability. Even if they are partly a flourish of verbal brinksmanship, his words help explain why the United States - more than other nations - perceives Tehran to be so dangerous that it is keeping the military option on the table.
One reason is that Iran and America have been avowed enemies since the 1979 hostage crisis, with Iran's clerics calling for the annihilation of the US. Yet it also seems clear that this administration - galvanized by 9/11 - sees Iran's words, too, as more than rhetoric, and sees itself as the only nation willing and able to take action.
"After 9/11, there was an awakening," says analyst Richard Perle, a member of the Pentagon's Defense Policy Board from 2001 to 2003. "The administration has to believe that it's possible to wait too long to deal with a problem, the contours of which could have been seen easily before. Is it safe to do that again?"
Clearly, the administration is not alone in its concerns. The prospects of a nuclear-armed Iran are sobering, and Mohamed ElBaradei, head of the International Atomic Energy Agency, is in Tehran this weekend for discussions about Iran's nuclear program. One of the clearest dangers comes from the instability of the region. As perhaps the most volatile area in the world, the Middle East could thus be the most susceptible to war, raising the possibility that Iran would actually use a bomb.
Yet even if it were never used, an Iranian nuclear weapon could have a transformative effect. For one, Iran could become bolder in its terrorist activities, knowing that nations would be less likely to retaliate. Moreover, a nuclear Iran would recalibrate the balance of power in the region, perhaps pressing Saudi Arabia or Turkey toward the development of its own nuclear weapons.
"What kind of arms races do we get into in the region?" asks Anthony Cordesman of the Center for Strategic and International Studies in Washington. "As you start to go down the list of uncertainties, it is a little difficult not to believe that the world wouldn't be far better off if Iran didn't proliferate."
While the stability of the Middle East - with its enormous oil and gas reserves - is of vital interest to the Bush administration, the president's pronouncements point to another, perhaps deeper concern about Iran's potential behavior.
The rule of the nuclear era has been deterrence: You won't attack me with nuclear arms because then I would attack you. The concern with Iran is twofold. One is that Iran could feed a nuclear device into a terrorist network, which would obscure the weapon's origin and make it impossible for the US to respond in kind. The other is that the strain of martyrdom in Shiite Islam - and the Iran regime's extremist ideology - could render deterrence meaningless.
Experts debate these points fiercely. But Bush's statements suggest that he is inclined not to dismiss Iran's threatenings. Just as Al Qaeda threatened America from afar before 9/11, then acted, there is the worry that Iran could do the same. "Another lesson of September the 11th is that we must deal with threats before they come to hurt us," Bush said in a March 9 speech. "Whenever we see a threat, the United States of America must take them seriously. We cannot take threats for granted."
The threat is greatest for Israel at the moment, and that, too, creates unique pressures for an administration that has firmly backed Israel. Analysts agree that, for now, the US is out of range of Iranian missiles. But that might not always be true, and Israel is well within range now. Iranian President Mahmoud Ahmadinejad has said Israel should be "wiped off the map" and that "we shall soon experience a world without the United States and Zionism" - tightening the already strong bond between the US and Israel.
"Israel is quite important to the US," says Richard Falkenrath, a former member of the Bush team who helped shape the administration's nuclear nonproliferation strategy. "Europe is not indifferent, but it's safe to say they care less."
It is one way America's attitude toward Iran diverges from those in Europe. In some respects, that divergence is part of what appears to be the administration's broader worldview, which has placed little faith in traditional allies and international organizations. "There's the sense that the US has been willing to lead, but other nations have been unwilling to do their part," says Ted Galen Carpenter, a foreign-policy analyst for the Cato Institute in Washington.
But the current crisis also highlights how history has colored America's attitudes toward Iran. "[Other countries] didn't have a hostage crisis. They didn't have a break in diplomatic relations like we did," says Mr. Falkenrath. "They have political ties and business ties that we lack."
Yet Europe is much more closely aligned with the US on Iran than it ever was on Iraq, many experts also suggest. Part of the Bush administration's fervor is a simple matter of timing, they say.
"Whatever the Bush administration has done, Iran has systematically escalated the issue," says Dr. Cordesman. "Until the [discoveries of an accelerated nuclear program] began in 2002, it was seen as a low-level threat." For the time being, he and others caution against overstating the immediacy of the threat, and the rhetorical vehemence of Bush's response. "It has been policy by statement," says Falkenrath. "There have been no [US] threats [to Iran]. No ultimatum. No timetable."
At the very least, Iran is still a year or two away from being able to build a nuclear weapon, and most analysts say Iran might not reach the threshold until 2010 or later. Many things could happen in the meantime that could increase the pressure for a military attack or eliminate it completely. "What reaction [we take] will depend on how these things play out," says Mr. Perle. "We're not there yet."