What to Do about Iran? Iran's decision to resume nuclear enrichment activities—a key step in the process of making nuclear weapons—is a direct challenge to the United States, Europe and the rest of the world. For more than two years now, Europe—with Washington's support—has offered Tehran a reasonable deal: End the nuclear enrichment work it had been doing in secret for nearly two decades and receive technical support for a civilian nuclear energy program as well as expanded economic and diplomatic ties. Last week, the new Iranian government of President Mahmoud Ahmadinejad basically told the international community to get lost. It resumed research and development activities that had been suspended during the talks with the Europeans, still claiming that its nuclear program was entirely peaceful. As Ger- man Chancellor Angela Merkel made clear on her visit to Washington this month, even those most committed to a diplomatic solution with Iran now accept that diplomacy has run its course, and the time for decision and action has arrived. But what decision, and what action? In the debate about how to respond to Iran, two opposing camps have emerged: One wants to give in to Iran the other wants to bomb it. Both are wrong. In the first camp are those—mostly in Europe, but also in many other parts of the world—who accept Tehran's argument that it has a right to develop nuclear technology for peaceful purposes. And while they would oppose an Iranian bomb, they argue that there is little we can do to prevent a determined Iran from building one eventually and that, in any case, a nuclear-armed Iran can be contained. It would be difficult to get international support for economic sanctions, they say, and even if Russia and China were somehow to agree to them, sanctions would fail to change policy—as in Iraq, North Korea and Cuba. This view is entirely too complacent. It's a delusion to believe that Iran's program is for civilian purposes only and that allowing Iran to master nuclear enrichment is therefore no big deal. Given Iran's long track record of hiding and lying about important aspects of its nuclear program, allowing it to develop enrichment and reprocessing capabilities—even under an international inspection regime—would remove the most important technical barrier to its acquiring nuclear weapons and leave the decision of going nuclear entirely in the hands of Ahmadinejad's radical Islamist government. That is an unacceptable risk. The dangers of an Iranian bomb are clear. Others—Saudi Arabia, Egypt, Turkey—could follow suit, both in order to deter Tehran and in the well-warranted belief that a world that allowed Iran to build a bomb would surely allow them to do so as well. This would be a fatal blow to the already shaky nuclear nonproliferation regime, which for nearly 40 years has helped convince countries as diverse as Sweden, South Korea, Brazil and Ukraine that the costs of acquiring nuclear weapons far outweigh the benefits. Moreover, a nuclear-armed Iran would represent a major threat to regional and global security. It could deter the United States and others from responding to Iranian aggression or to Tehran's support for terrorism in the Middle East and beyond. And given the messianic streak of Tehran's current leaders, do we really want to run the risk of them passing nuclear materials or even a weapon on to al Qaeda(基地组织)? On the other side of the debate are those—mostly in the United States—who think that the time has come to use military force against Iran. Because diplomacy has failed and we are, as President Bush has said, 'all sanctioned- out' as far as Iran is concerned, the only option left is a military strike against Iran's nuclear facilities before it is too late. If ever there were a ease, they argue, for making good Bush's vow—that America will 'not allow the world's most dangerous regimes to posses