What to do about Iran's determination to have nuclear weapons?

A few days ago, an Iranian nuclear scientist was mysteriously blown to pieces -- after at least four others had met the same fate in similar shadowy episodes.

International inspectors, meanwhile, reported that Iran is enriching uranium, a step on the road to creating a nuclear weapon. Iranian officials responded to the prospect of stepped-up economic sanctions by threatening to close the vital Strait of Hormuz, which would choke off much of the world's oil supply and send energy prices soaring. On top of everything else, an American Marine veteran, held in Iran on espionage charges, was sentenced to death.

Ultimately, this is all about the bomb. The United States and its allies are at loggerheads with Iran because it is pursuing the capability of making a nuclear weapon. Fortunately, there are signs the Iranians haven't yet decided to actually build one. So the question now is, what can the rest of the world do to keep this particular country out of the nuclear club? And just how bad would it be if Iran really did go nuclear?

First, it's time to face the fact that the world has few good choices to prevent Iran from building a bomb if it really wants to. Sanctions are taking a serious toll, but by themselves are unlikely to dissuade Iran, whose rulers have ruthlessly crushed political opposition and do not seem to mind imposing economic hardship on their people.

Covert actions, including the killing of scientists and the use of Stuxnet, a computer virus that wiped out a chunk of Iran's nuclear centrifuges, may postpone a bomb but could fuel a damaging cycle of tit-for-tat retaliation -- and harden Iranian resolve. Even a pre-emptive attack would only delay the Iranian program, unless it was followed by a more or less permanent occupation of the country. And there is no guarantee that such a costly attack could locate and destroy the right Iranian facilities.

On the other hand, the spread of nuclear weapons to Iran, however troublesome, isn't the end of the world. Israel and Pakistan, in the immediate neighborhood, have nuclear weapons and haven't used them. Nor has anyone else since America dropped two on Japan. Nuclear weapons may well be unusable; Israel has overwhelming nuclear firepower and second-strike capabilities, meaning it would be suicidal for Iran to attack it with nuclear arms. It's conceivable Iran could give terrorists a concealable nuclear device, but that would be extremely risky and technologically difficult.

Still, the world would be a better place without a nuclear-armed Iran, which would probably be emboldened by its new weapons to throw its weight around even more destructively in the region. So it's worth trying to nudge it in a different direction.

Doing this takes an understanding of Iran's motivation. A history of meddling by western powers, including a CIA-backed coup in 1953, has fueled distrust on the part of Iran, which has long struggled to balance secular and clerical power. These forces exploded in the 1979 overthrow of the shah and the seizure of more than 60 American hostages. Since 9/11, moreover, the United States has invaded two of Iran's neighbors. What seems to us like paranoia looks to Iranians like justifiable security concerns. Iran also aspires to dominate its oil-rich region, and is a sworn enemy of Israel. But it knows that bucking the world to develop nukes will be costly indeed.

At this point, threats and low-level violence will only make compromise harder, while raising the risk of armed conflict. The last thing America needs right now is another Middle Eastern war. Our best approach, therefore, is a policy of tough sanctions, international cooperation and toned-down rhetoric.

Both sides must understand that the only sensible solution is a negotiated outcome, probably allowing Iran to enrich nuclear fuel for peaceful ends under close international supervision -- with no bomb-making.