Washington

WITH the Iranian nuclear crisis about to land in the Security Council, the events that led up to the war in Iraq point clearly to what needs to be done.

In the decade preceding the Iraq war, Mr. Hussein was able to defy the major powers when they were divided. Exploiting his advantage as a single actor and Washington's indecision over whether it most wanted nonproliferation or regime change, Mr. Hussein consistently outmaneuvered his diplomatic opponents.

But he also knew that he could not buck the five permanent members of the United Nations Security Council when they were serious and united (as, for example, during the toughened United Nations inspections in the months just before the war), and he did not even try.

The situation with Iran today is the same. Washington cannot decide whether the top priority of its Iran policy should be regime change or nonproliferation; as a result, others of the major powers do not trust and will not fully support its antinuclear efforts. Tehran has easily exploited this lack of unity among the major powers to frustrate every attempt to rein in its nuclear program. It has recruited international support through energetic diplomacy to the group of developing countries known as the G-77. Just as Mr. Hussein did, the leaders in Tehran have made diplomatic mincemeat of the big powers.

Iran has been so successful in this that some experts in the West have turned defeatist. Their view is mistaken. The idea that "it's too late" to stop Iran's progress toward building nuclear weapons is technologically wrong. "There's nothing we can do about it" ignores a range of options between economic sanctions, going to war and more of doing nothing. And the argument that "we can learn to live with it" misses the nature of the challenge.

A nuclear Iran is dangerous enough, but this crisis is only proximately about Iran. More important, it is about the likely consequence of an Iranian bomb, namely, that Saudi Arabia, Turkey and Egypt would produce their own bombs, and, thanks to the concomitant international failure to deal with North Korea, the nonproliferation regime would collapse. What is at stake is not a choice between 9 and 10 nuclear weapons states, but a choice between 9 and 30 or more.

The major powers may yet be able to unite to stop Iran at this late hour, but not without a decisive change in American policy. Washington's choice is simple: does it want to stop Iran's acquisition of nuclear weapons badly enough to deal with Iran's present government?

Like the Clinton administration with Iraq, the Bush administration has been unable to make up its mind, locking its policy into a cycle of self-defeating half-steps. The combination of "axis of evil" threats, partial support of European negotiations and publicly announced financial backing for the opposition in Iran ensures only that we will fail either to negotiate an end to the nuclear program or to overthrow the present regime.

The administration must, finally, hold its nose and recognize that the nuclear challenge is the indisputable priority. It must get off the sidelines and into negotiations with Tehran. It must solidify agreement among its fellow permanent council members by working closely with Russia, not least by concluding a long overdue pact on civil nuclear cooperation. Russian participation would make it possible to provide Iran with a credible international guarantee of uranium enrichment and reprocessing services.