I ran has agreed to suspend its nuclear programs while it continues negotiations with European nations on the future of those efforts. While the government in Tehran is pleased with the results of the discussions, other nations, worried about the possible proliferation of nuclear weapons, should be more cautious. This is the second deal the parties have signed; the speed with which the first came apart is grounds for concern. In addition, contrary to many reports, Iran has not agreed to end its nuclear program, merely to suspend it. The final outcome will show how serious the world is about halting the spread of nuclear weapons.

Iran has long had a nuclear energy program. Since its inception, there were questions about its nuclear weapons ambitions, but Tehran always denied that it wanted anything other than a peaceful, civilian program. Those assurances were deflated two years ago when an Iranian exile group provided accurate information about secret facilities that were being used for uranium enrichment and conversion. An intensive investigation by the International Atomic Energy Agency has not yielded evidence that Iran is trying to build a bomb, but suspicions have increased with the discovery of weapons-grade uranium on enrichment centrifuges and Iran's admission that it produced small amounts of plutonium.

Last October, Britain, France and Germany tried to head off a crisis and negotiated a deal that would suspend Iran's nuclear programs. The agreement allowed Iran to avoid official censure by the IAEA -- which was being pushed by the United States -- and would have obliged the U.N. Security Council to take up the matter. That deal quickly unraveled amid a dispute over terms.