Iran's government therefore has to make an active choice to build the bomb. And in a country where the political system is neither democratic nor strictly dictatorial, that kind of decision would have to be made by a group of people often paralyzed by division.

While there is no way to know for sure, many Iran experts agree that Iran most likely does not have a nuclear weapon because there is as yet no consensus in the political leadership in favor of weaponization. This is good news, because without such consensus, there can be no Iranian weapons program. No amount of anti-Semitic, anti-American, terrorist-sponsoring, hate-filled vitriol from the mullahs in Tehran is enough to give them the bomb without their political leadership actively deciding to acquire it. An Iran with a nuclear program is different from an Iran with a nuclear weapons program, and it is the Iranian leaders, elected and appointed, who decide which way it will actually be.

Iran's motivations for pursuing nuclear technology often go unanalyzed in the U.S Much of the Washington policy establishment takes it as a given that Iran wants the bomb. And there are plenty of reasons why we in the U.S. see Iran as dangerously aggressive: Iran's leaders deny the Holocaust while sponsoring terrorist organizations, they funnel arms to America's enemies in Iraq and Afghanistan, and they brutalize their own people.

There are also plenty of reasons why Iran might actually want to acquire the ultimate weapon. The U.S. has surrounded much of the country with a major military presence in the region, leaders in Washington and Tel Aviv frequently threaten to attack or overthrow the regime, and the world community has distrusted and squeezed the Islamic Republic since it came into existence in 1979.

Putting aside our (often correct) mistrust of the Iranian regime, what are, from Iran's perspective, the reasons not to go on a crash program for the bomb?

Nonproliferation experts believe that there are three basic reasons countries get nuclear weapons: security, prestige, and domestic politics. From the security perspective, an Iranian decision to acquire nuclear weapons would almost surely place the regime in greater short-term danger. An announcement from Tehran that it is seeking weaponization would give the green light for an American or Israeli attack, and would strengthen calls in the U.S. for an active policy of regime change. The global community would be unlikely to oppose an American or Israeli preemptive strike. Nor would Iran fare much better if it went forward with a secret program that was discovered mid-production -- a likely prospect given how many of Iran's secret activities have been exposed over the past decade.

On the other hand, perhaps the greatest security argument in favor of a bomb is the prospect of creating a deterrent against outside attack -- call it the North Korean model. It's not hard to see how some in Iran might take a lesson from Libyan leader Muammar Qaddafi, who gave up his nuclear program and is now facing a NATO campaign that threatens his rule. This might lead Iranian leaders to believe acquiring a bomb is their best shot at long-term survival. But such a plan could also backfire. If Iran were to succeed in building a bomb, its strategic position could be placed in greater danger by a nuclear arms race in the region, with Saudi Arabia the most likely to move for a weapon of its own. Plus, the West's strategic calculus would shift dramatically, potentially escalating the greatest external threat facing Tehran from one of limited surgical strikes to a much larger military attack or even a nuclear standoff. That is why Iran's nuclear envoy says it would be a "strategic mistake" to build a bomb, and it is likely why Supreme Leader Ayatollah Ali Khamenei is said by Western intelligence agencies to feel the same way.