Iran brags that it has the most crucial technologies for a nuclear bomb. It is known to be deploying long-range missiles that would be militarily useless unless equipped with a nuclear warhead. And it has insisted that it will continue to enrich uranium in defiance of a request by the United Nations to stop.
What's more, President Bush and Sen. John F. Kerry each has said an Iranian nuclear bomb would be unacceptable to the United States; Israeli Prime Minister Ariel Sharon's rhetoric is even tougher. Given all this, what are the prospects that U.S. military force or Israeli military force with tacit or public U.S. backing will be used to stop Iran's nuclear program?
The first hope is that Iran's program can still be stopped via diplomacy. It is not out of the question that Iran will step back from its nuclear program scaling it back and slowing it down, if not dismantling it entirely if confronted by the international community with a stark choice: penalties if the nuclear program continues, benefits if it is stopped.
But such a choice, of course, is effective only if Iran's hard- liners believe that the penalties for proceeding will be serious and it is hard to come up with a set of meaningful and plausible penalties that do not involve the military.
Comprehensive sanctions like those imposed on Iraq seem unlikely. Who would propose banning Iran's 2.5 million barrels a day of oil exports when oil prices are so high?
So is military force a realistic option? An air raid on Iran's nuclear facilities, similar to Israel's 1981 raid on Iraq's Osirak reactor, would face many problems. First, we probably do not know about all of Iran's many facilities. What we do know shows that Iran's nuclear program is physically dispersed and designed to be rebuilt after raids. We can hope that Iran would react to a raid by deciding that its nuclear program was not worth the cost, but if Iran decided instead to rebuild, then our raid might only slow the program by two years.
Plus, if we struck, Iran could retaliate by laying mines in and around the Strait of Hormuz at the entrance to the Persian Gulf. That could drive world oil prices even higher. Even more worrisome, Iran has many options for stepping up its support for terrorism in Iraq, against Israel or through aid to Al Qaeda.
And then there's the fact that we could end up paying a high price in international public opinion for a raid against Iran, jeopardizing the willingness of other governments to join with us in putting pressure on Iran.
In other words, a raid on Iran's nuclear facilities might buy some time, but only at considerable cost. And all these problems apply equally or more so if the raid on Iran's facilities were carried out by Israel (which in any case would have to stretch its capabilities to mount a raid on sites so far from its borders twice as far as Osirak in Iraq).
An actual invasion of Iran is even less appealing than an Osirak-style raid. There is the obvious cost in lives and dollars, as well as the sobering lesson from Iraq about postwar stability. Most Iranians would welcome the end of the mullahs' regime, but not a U.S. occupation. And there would be a hard core of Islamist militants whose terrorism could undermine stability.
There is an even more basic problem. Operations in Iraq are already straining the U.S. military, which simply does not have the men or the equipment to invade Iran unless there was a massive national mobilization which would take at least a year and possibly much longer for the U.S. to prepare.
That said, there are military options against Iran other than an Osirak-style raid or an invasion. In an ideal world, the United States could disrupt Iran's nuclear program through covert means, such as corrupting software programs. But it is not clear if U.S. intelligence is in a position to do this.
What America can do both on its own and with allies is to contain and deter Iran. Steps to this end could include increasing U.S. military presence around Iran; putting nuclear weapons on U.S. ships off Iran's coast; reinforcing the region's protection against missiles (including accelerating the planned improvement to the Arrow antimissile system in Israel); extending an explicit nuclear umbrella to those threatened by Iran; transferring more advanced weapons to states around Iran (from NATO ally Turkey to the new Iraqi forces to the more stable Arab Gulf states); and so on.
None of these measures is as dramatic as an air raid, but as a package they could show Tehran that Iranians will be less secure if it pursues nuclear weapons. Containment and deterrence can be used to press Iran to accept a diplomatic solution, and they also enhance the ability of the U.S. to apply military force later if need be.
In short, there is a wide range of military options to step up pressure on Iran if we think creatively; we do not need to start by dropping bombs.
Mr. Clawson is deputy director of the Washington Institute for Near East Policy.