Given Tehran's defiant response to the European and American effort to constrain its nuclear program, it is time for bolder diplomacy out of Washington. U.S. President George W. Bush should take a page from the playbook of Ronald Reagan, who negotiated with an evil Soviet regime--competing in the war of ideas, but addressing the enemy's security concerns through arms-control agreements.

Iran's intransigence is both deeply unfortunate and perfectly predictable. It is unfortunate because Tehran's refusal to suspend its uranium-enrichment operations immediately--as demanded in July by the U.N. Security Council in a legally binding resolution--suggests that Iran is moving more quickly than expected toward a nuclear-weapons capability. Tehran has now turned the nuclear crisis into a test of the whole U.N. Security Council system. And Russia and China's current position, threatening to veto any biting sanctions against Iran, suggests that the Security Council may well fail this crucial test.

Tehran's response is predictable, however, because the offer on the table contains both inadequate economic carrots and barely credible threats of sanctions and military force. The carrots appeared impressive at first glance--in return for a suspension of enrichment we reportedly promised to provide light-water nuclear reactors and to help Iran with civil aviation and telecommunications technology. But we did not offer the one incentive that might possibly work, security guarantees that could reduce Iran's desire for nuclear weapons.

This omission is striking. The Iranian government can't talk openly about their security concerns because that would blow their cover story that the nuclear program is only for energy production. And Washington does not want to discuss such worries because it wants to keep open the possibility of removing the regime by force. "Security assurances are not on the table," U.S. Secretary of State Condoleezza Rice too cleverly argued this spring: "It is a little strange to talk about security guarantees ... I thought the Iranian position was that they weren't developing a nuclear bomb."

This is partly a crisis of our own making, as the Bush administration has practiced the reverse of Teddy Roosevelt's maxim--speaking loudly and carrying a small stick. Think about how Tehran reacted when Bush stated (in his second Inaugural Address), "The rulers of outlaw regimes can know that we still believe as Abraham Lincoln did: 'Those who deny freedoms to others deserve it not for themselves; and, under the rule of a just God, cannot long retain it." Or when Bush dramatically told reporters last April that "all options are on the table," in direct response to a question about whether he was considering a nuclear attack against Iran. Such statements only encourage Iran to develop a nuclear deterrent quickly, before the United States can carry out its perceived aggressive intent. Last month, Iran's National Security Council Secretary Ali Larijani pointedly complained about such rhetoric. "How can a side that wants to topple the regime also attempt to negotiate?"

Given the current vulnerability of U.S. forces in Iraq, the deteriorating situation in Afghanistan, and the lack of Israeli success against Hizbullah, Iranian officials seem confident that they face no immediate threat of a U.S. military assault. But they are clearly worried that Bush just might attack Iran right before he leaves office in January 2009, or that his successor might do so once U.S. forces withdraw from Iraq.

The best way to prevent a nuclear Iran is for Washington to offer the kind of security assurances that might reduce support in Tehran for building a nuclear arsenal. It will be hard to make such assurances credible, but a public U.S. promise to take forcible regime change off the table, and a U.N. Security Council commitment to protect the "political sovereignty" of Iran could help. Involving the Security Council could also pull China and Russia back into the nonproliferation coalition and enhance the U.N.'s legitimacy.

There is very little time left, which means negotiations should begin despite Iran's unfortunate opening position. Tehran's response reportedly indicated a willingness to negotiate all aspects of its nuclear program, so working out an agreement for Iran to limit itself to low-level uranium enrichment might still be possible. This would work only if Tehran accepts full IAEA inspections and a freeze on future centrifuge construction. Will they? The one thing that might cause Tehran to do so, and that would compensate for any loss of face, would be an assurance that the United States will not launch another preventive war, as it did in Iraq, to remove the Iranian regime. If in turn we get a nuclear-free Iran, that's a good deal for the West as well.

One day perhaps Marina Agaltsova will join the diplomatic corps at a foreign embassy, or help write policy positions for the Russian government. Coit Blacker hopes that the lessons from her Stanford-sponsored distance-learning course will stick.

Agaltsova was among a group of Russian students brought to the provincial city of Yaroslavl in late May for an academic conference that capped this year's five distance-learning courses offered at nine universities across Russia by the Initiative on Distance Learning at the Freeman Spogli Institute for International Studies.

Through videotaped lectures, web readings and online chat sessions with senior research scholar Kathryn Stoner-Weiss and 14 other Stanford instructors, students in Democracy, Development and Rule of Law explored democratic ideals and practices, studying examples in Latin America, Asia and the former Soviet Union. "The course taught me that there is a black side to the reforms" that followed perestroika in Russia, Agaltsova says. "I learned more about Russian history [in the course] than I had learned in school."

That's the idea, says FSI director Blacker, who wants to re-establish the teaching of critical analysis, lost under decades of Communist rule, in Russian universities. "The social sciences were disemboweled," he says. He wants to develop future generations of diplomats and policy makers whose worldview is shaped "by how they think, not what they're told to think."

This year, to cap off the courses, 40 students came to Yaroslavl to participate in a mock United Nations Security Council session addressing Iran's nuclear program. They traveled from the farthest reaches of the Russian hinterlands, like Amur State University in Blagoveschensk, 4,800 miles from Moscow.

The arms control simulation is a teaching tool developed for the Stanford undergraduate class International Security in a Changing World, taught by Blacker and Scott Sagan, a political science professor and director of the Center for International Security and Cooperation within FSI. Sagan has exported the simulation to several universities in the United States where his former graduate students now teach--UC-Berkeley, Dartmouth, Columbia, Duke--but this was the first one he has conducted overseas.

This year's scenario was the International Atomic Energy Agency's referral of Iran to the U.N. Security Council for failure to fully disclose its nuclear activities. During the simulation, students submitted proposals to their heads of state, played by Blacker, Sagan and Russian faculty members. By the end of the two-day session, delegates had overcome seemingly intractable differences during four intensive sessions led by Stanford third-year law student Matthew Rojansky, acting as U.N. undersecretary-general for legal affairs. The council's resolution gave Iran three months to comply with the IAEA's requests and provided for Iran to obtain nuclear fuel from Russia, with the production and waste disposal to occur on Russian soil under IAEA controls.

After the session closed, students set aside their delegate roles to reflect on what they had learned. Narina Tadevosian, a student from Yakutsk State in far eastern Siberia, said she was surprised at "how strict Russia was" in taking a leading role in the session.

"If only it were so in real life," she added.

North Korean technicians are reportedly in the final stages of fueling a long-range ballistic missile that some experts estimate can deliver a deadly payload to the United States. The last time North Korea tested such a missile, in 1998, it sent a shock wave around the world, but especially to the United States and Japan, both of which North Korea regards as archenemies. They recognized immediately that a missile of this type makes no sense as a weapon unless it is intended for delivery of a nuclear warhead.

A year later North Korea agreed to a moratorium on further launches, which it upheld -- until now. But there is a critical difference between now and 1998. Today North Korea openly boasts of its nuclear deterrent, has obtained six to eight bombs' worth of plutonium since 2003 and is plunging ahead to make more in its Yongbyon reactor. The six-party talks aimed at containing North Korea's weapons of mass destruction have collapsed.

Should the United States allow a country openly hostile to it and armed with nuclear weapons to perfect an intercontinental ballistic missile capable of delivering nuclear weapons to U.S. soil? We believe not. The Bush administration has unwisely ballyhooed the doctrine of "preemption," which all previous presidents have sustained as an option rather than a dogma. It has applied the doctrine to Iraq, where the intelligence pointed to a threat from weapons of mass destruction that was much smaller than the risk North Korea poses. (The actual threat from Saddam Hussein was, we now know, even smaller than believed at the time of the invasion.) But intervening before mortal threats to U.S. security can develop is surely a prudent policy.

Therefore, if North Korea persists in its launch preparations, the United States should immediately make clear its intention to strike and destroy the North Korean Taepodong missile before it can be launched. This could be accomplished, for example, by a cruise missile launched from a submarine carrying a high-explosive warhead. The blast would be similar to the one that killed terrorist leader Abu Musab al-Zarqawi in Iraq. But the effect on the Taepodong would be devastating. The multi-story, thin-skinned missile filled with high-energy fuel is itself explosive -- the U.S. airstrike would puncture the missile and probably cause it to explode. The carefully engineered test bed for North Korea's nascent nuclear missile force would be destroyed, and its attempt to retrogress to Cold War threats thwarted. There would be no damage to North Korea outside the immediate vicinity of the missile gantry.

The U.S. military has announced that it has placed some of the new missile defense interceptors deployed in Alaska and California on alert. In theory, the antiballistic missile system might succeed in smashing into the Taepodong payload as it hurtled through space after the missile booster burned out. But waiting until North Korea's ICBM is launched to interdict it is risky. First, by the time the payload was intercepted, North Korean engineers would already have obtained much of the precious flight test data they are seeking, which they could use to make a whole arsenal of missiles, hiding and protecting them from more U.S. strikes in the maze of tunnels they have dug throughout their mountainous country. Second, the U.S. defensive interceptor could reach the target only if it was flying on a test trajectory that took it into the range of the U.S. defense. Third, the U.S. system is unproven against North Korean missiles and has had an uneven record in its flight tests. A failed attempt at interception could undermine whatever deterrent value our missile defense may have.

We should not conceal our determination to strike the Taepodong if North Korea refuses to drain the fuel out and take it back to the warehouse. When they learn of it, our South Korean allies will surely not support this ultimatum -- indeed they will vigorously oppose it. The United States should accordingly make clear to the North that the South will play no role in the attack, which can be carried out entirely with U.S. forces and without use of South Korean territory. South Korea has worked hard to counter North Korea's 50-year menacing of its own country, through both military defense and negotiations, and the United States has stood with the South throughout. South Koreans should understand that U.S. territory is now also being threatened, and we must respond. Japan is likely to welcome the action but will also not lend open support or assistance. China and Russia will be shocked that North Korea's recklessness and the failure of the six-party talks have brought things to such a pass, but they will not defend North Korea.

In addition to warning our allies and partners of our determination to take out the Taepodong before it can be launched, we should warn the North Koreans. There is nothing they could do with such warning to defend the bulky, vulnerable missile on its launch pad, but they could evacuate personnel who might otherwise be harmed. The United States should emphasize that the strike, if mounted, would not be an attack on the entire country, or even its military, but only on the missile that North Korea pledged not to launch -- one designed to carry nuclear weapons. We should sharply warn North Korea against further escalation.

North Korea could respond to U.S. resolve by taking the drastic step of threatening all-out war on the Korean Peninsula. But it is unlikely to act on that threat. Why attack South Korea, which has been working to improve North-South relations (sometimes at odds with the United States) and which was openly opposing the U.S. action? An invasion of South Korea would bring about the certain end of Kim Jong Il's regime within a few bloody weeks of war, as surely he knows. Though war is unlikely, it would be prudent for the United States to enhance deterrence by introducing U.S. air and naval forces into the region at the same time it made its threat to strike the Taepodong. If North Korea opted for such a suicidal course, these extra forces would make its defeat swifter and less costly in lives -- American, South Korean and North Korean.

This is a hard measure for President Bush to take. It undoubtedly carries risk. But the risk of continuing inaction in the face of North Korea's race to threaten this country would be greater. Creative diplomacy might have avoided the need to choose between these two unattractive alternatives. Indeed, in earlier years the two of us were directly involved in negotiations with North Korea, coupled with military planning, to prevent just such an outcome. We believe diplomacy might have precluded the current situation. But diplomacy has failed, and we cannot sit by and let this deadly threat mature. A successful Taepodong launch, unopposed by the United States, its intended victim, would only embolden North Korea even further. The result would be more nuclear warheads atop more and more missiles.

Ashton B. Carter was assistant secretary of defense under President Bill Clinton and William J. Perry was secretary of defense. The writers, who conducted the North Korea policy review while in government, are now professors at Harvard and Stanford, respectively.

North Korea's nuclear facility at Yongbyon, which had been "frozen" under international inspection since 1994, was reactivated this January for the production of plutonium. Just last week the North Koreans announced that they intended to use the resulting plutonium to make nuclear weapons, which only confirmed what we always believed.

If it keeps on its present course, North Korea will probably have six to eight nuclear weapons by the end of the year, will possibly have conducted a nuclear test and may have begun deployment of some of these weapons, targeted against Japan and South Korea. By next year, it could be in serial production of nuclear weapons, building perhaps five to 10 per year.

This is a nightmare scenario, but it is a reasonable extrapolation from what we know and from what the North Koreans have announced. The administration to this point has refused to negotiate with North Korea, instead calling on the countries in the region to deal with the problem. The strategy underlying this approach is not clear, but the consequences are all too clear. It has allowed the North in the past six months to move from canned fuel rods to plutonium and, in a few more months, to nuclear weapons. And the consequences could extend well beyond the region. Given North Korea's desperate economic condition, we should expect it to sell some of the products of its nuclear program, just as it did with its missile program. If that happens, a nuclear bomb could end up in an American city. The administration has suggested that it would interdict such transfers. But a nuclear bomb can be made with a sphere of plutonium the size of a soccer ball. It is wishful thinking to believe we could prevent a package that size from being smuggled out of North Korea.

How did we get into this mess?

For several decades North Korea has aspired to have nuclear weapons. During that period successive administrations have, through a combination of threats and inducements, curtailed their program but never their aspirations. In the late 1980s the first Bush administration saw the potential danger and persuaded the Soviet Union to pressure North Korea to join the nuclear Non-Proliferation Treaty and subject its nuclear facilities to international inspection. The North Koreans complied, but they stalled long enough to give them time to make and store enough plutonium for one or two nuclear bombs before the inspectors arrived.

Shortly after the Clinton administration took office, they tried again. As spent fuel was being taken from the nuclear reactor at Yongbyon, the North Koreans ejected the inspectors and began preparations for reprocessing. This would have given them enough plutonium for five or six additional nuclear bombs. President Clinton considered this sufficiently dangerous that he declared reprocessing a "red line." In response, I had the Joint Chiefs prepare a plan to use military force if necessary to prevent this outcome. When Kim Il Sung offered to negotiate the issue, Clinton responded that he would negotiate only if the North Koreans froze all activity at Yongbyon during the negotiation. In the end, military force was not necessary. The agreement that ended this crisis was far from perfect, but in its absence North Korea could today have 50 to 100 nuclear weapons.

But the North Koreans never gave up their desire for nuclear weapons. Even as they complied with the freeze at Yongbyon, they covertly started a second nuclear program at a different location. American intelligence discovered signs of this program and last fall confronted the North Koreans, who did not dispute the charge. The administration responded by stopping fuel oil deliveries called for under the old agreement, to which the North Koreans responded by reopening Yongbyon and racing to get nuclear weapons.

There are three basic approaches for dealing with this dangerous situation. The administration can continue to refuse to negotiate, "outsourcing" this problem to the concerned regional powers. This approach appears to be based on the hope that the regional powers will be able to prevail on North Korea to stop its nuclear program. But hope is not a strategy. If their hopes are not realized and North Korea continues on its present course, it will soon have a significant nuclear arsenal. And while the regional powers could play a role in resolving this crisis, they are unlikely to succeed in the absence of a clear American negotiating strategy in which they can participate.

A second alternative is to put economic pressure on North Korea and hope for "regime change." Or the United States could take military action to bring this change about. But while the regime may one day collapse, with or without economic pressure, there is no reason to believe that it will happen in time - the nuclear threat is imminent. Taking military action to force a timely regime change could result in a conflict comparable to the first Korean War, with casualties that would shock the world.

The third alternative is to undertake serious negotiations with the North Koreans to determine if there is a way to stop their nuclear program short of war. The administration is clearly reluctant to negotiate with the North Koreans, calling them loathsome and cheaters. It is easy to be sympathetic with this position; indeed, the only reason for considering negotiation with North Korea is that the other alternatives are so terrible. The administration, seeing the danger, has said that it "would not tolerate" a North Korean nuclear arsenal. The North Koreans responded to this declaration by accelerating their program. The conflict between our views and their actions is a formula for drifting into war. It is imperative that we stop that drift, and the only clear way of doing that is by negotiating.

Any negotiations with the North Koreans are likely to be difficult and protracted, so they should be predicated on a prior agreement that North Korea will freeze its nuclear activities during the negotiations. For negotiations to have a chance of success, they would need to have a positive dimension, making it clear to North Korea that forgoing nuclear weapons could lead it to a safe and positive future. But they would also need a negative or coercive dimension, both to induce North Korea to take the right path and to give us and our allies more credible options if diplomacy should fail. President Kennedy said it best: "We should never negotiate from fear, but we should never fear to negotiate."