It's been more than a year since President Bush tagged Iraq, North Korea, and Iran as an "axis of evil" for their past support of terrorism. Since then, all three nations have been caught flouting international agreements on weapons of mass destruction.
The latest is Iran, the most powerful nation of the three. Last month, the International Atomic Energy Agency (IAEA) confronted the Islamic republic for not reporting that it had opened a plant that can produce bomb-grade uranium.
Iran has signed the Nuclear Non-Proliferation Treaty, under which it is allowed to build a 1,000-megawatt light-water reactor for electricity at Bushehr, under the watchful eye of the IAEA.
But a dissident Iranian group blew the whistle on the secret plant, creating doubts about the IAEA's credibility as a nuclear watchdog and a potential next crisis in the US-led war on terrorism.
While Iran's Islamic leaders claim the plant is for peaceful purposes, they nonetheless defend their right to develop nuclear weapons. They point out Iran lives under the shadow of Israel and Russia, both nuclear powers.
But if the plant is truly for peaceful uses, than Iran must agree to the IAEA's request to monitor it. If not, the United States will be in the difficult position of deciding whether to threaten Iran as it has Iraq, or use diplomacy as it is doing with North Korea.
One big difference is that Iran has a semblance of democracy, albeit one constrained by an Islamic theocracy. Many of its elected leaders, such as President Mohammad Khatami, know that Iran must develop its economy quickly to meet the rising aspirations of a large population of young people. Iran also needs US support in taking such steps as joining the World Trade Organization.
A preemptive attack on Iran's nuclear processing plant would seem highly premature. Yet such a step is probably not ruled out by the Bush administration under its new security doctrine, since Iran has a clear history of supporting terrorist groups.
But with European help, especially from Britain and Prime Minister Tony Blair, the US should have enough diplomatic levers for now to keep Iran from making a nuclear bomb.