Unacceptable.

FOUR years ago, President Bush said his administration would not "permit the world's most dangerous regimes to threaten us with the world's most destructive weapons." Yet precisely that is about to happen. With Iran's announcement that it has begun uranium enrichment, we know that the world's most dangerous regime is on a fast track to building an atomic bomb.

Atomic bombs are only as scary as the regimes that own them--but this one is about as bad as they come. The mullahs would surely threaten us with their arsenal to extract concessions inimical to our interests, and might even be evil enough to launch their nukes. Consider Hashemi Rafsanjani, that celebrated "moderate," exulting that the Muslim world will "vomit [Israel] out from its midst," since "a single atomic bomb has the power to completely destroy [it]." Nuclear deterrence operates on the assumption that your foe is rational. Things break down when much of its ruling establishment fancies itself on a divine mission to evaporate the Zionist Entity, roll back the Great Satan, and usher in a paradisiacal rule by sharia. That's not a regime to bargain with. The goal must be to remove it from power.

This doesn't mean invasion and occupation. But it does mean getting serious about supporting the Iranian democracy movement. There are three things we should do now. First, give financial backing to Iranian labor unions so that workers--many of whom are deeply discontent with their government--can feed their families if they go on strike. Second, help Iranian student groups. Roughly 70 percent of Iran's population is under 30. These youths are the most pro-Western segment of Iranian society--and they are mad as hell at Iran's rulers. We should open channels of communication with student leaders, and repeat their message at every turn. Accordingly, our third priority should be to massively increase our pro-democracy broadcasts into Iran.

None of this is guaranteed to spark a revolution, but it has better odds than doing nothing. The sad consequence of our delay--and the world's indifference--has been to make military action more likely. While a bombing campaign can't stop Iran from eventually building nukes, it can delay that outcome by several years. But then what? If the mullahs stay in power, all that will change is the intensity of their lust for a bomb. We shouldn't hesitate to use military force if that's what it takes to keep them from getting one, but no air strikes will be effective over the long term unless coupled with an aggressive strategy to topple the regime from within.

Make no mistake: Bombing Iran is not a good option. The mullahs would probably retaliate with terrorist attacks against U.S. interests worldwide, as well as efforts to destabilize Iraq. But the alternative--letting them go nuclear--is incalculably worse. For a quarter-century they have been fighting an undeclared war against the West with the only weapons they have had: terrorism and a poisonous ideology. For a quarter-century we have failed to respond. They now stand on the brink of getting a new weapon--and this one will let them threaten the incineration of millions of infidels at the push of a button. Is this something that we--that anyone--should be willing to live with?