The strategic decision by the United States to nuke Iran was probably made long ago. Tactics adjust to unpredictable events as they unfold.

There was such an event last week, when Iran's president declared that Israel must be "wiped off" the map. The surprise was not the statement, which was an often-repeated quote by the late Ayatollah Khomeini, directed at a domestic student audience. What was surprising was both the timing (amid discussions about whether Iran should be allowed to enrich uranium) and the relatively low-key U.S. response. Tony Blair expressed "revulsion," Chirac was "profoundly shocked," the European Union in a joint statement "condemned [it] in the strongest terms." Instead, Bush was quiet.

White House Spokesman Scott McClellan commented, "It underscores the concerns we have about Iran's nuclear intentions," and the usually vociferous U.S. ambassador to the UN John Bolton only said that Ahmadinejad's remarks about Israel were "pernicious and unacceptable." Those are uncharacteristically mild statements for this administration in the face of such a provocative statement by Iran against one of the U.S.' closest allies. Why?

Because Iran's intended underlying message to the U.S., which was ill-timed only in appearance, was: If you nuke us, the world will know that you did it because Iran supports the Palestinian cause.

Instead, it is in the U.S.' interests to de-emphasize any suggestion to that effect, hence its low-key response. Because nuking Iran for threatening Israel will inflame the Arab world and will not be acceptable to our European allies nor even to the American public. There are many other justifications that the Western world and the American public will find more acceptable, and these will be emphasized by the Bush administration at the right moment.

Iran "is determined to get nuclear weapons deliverable on ballistic missiles that it can then use to intimidate not only its own region but possibly to supply to terrorists." (John Bolton, Oct. 15, 2005)

"We cannot let Iran, a leading sponsor of international terrorism, acquire the most destructive weapons and the means to deliver them to Europe, most of central Asia and the Middle East, or beyond." (John Bolton, June 24, 2004)

"[S]yria and Iran … share the goal of hurting America. … State sponsors like Syria and Iran have a long history of collaboration with terrorists…." (George Bush, Oct. 6, 2005)

The 9/11 Commission determined that al-Qaeda had long-standing and strong ties to Iran, for example that "senior al-Qaeda operatives and trainers traveled to Iran to receive training in explosives." (By contrast, it found no ties between al-Qaeda and Iraq).

Iran was responsible for the 1996 Khobar Towers bombing, where 19 Americans were killed and 372 wounded, according to a June 2001 indictment by the U.S. attorney general. According to the 9/11 Commission, al-Qaeda may also have been involved.

Hezbollah, a terrorist group tied to Iran, carried out the suicide bombing in Beirut that killed 241 U.S. Marines in 1982. Iran was directly involved, according to a ruling by U.S. District Court Judge Royce Lamberth in May 2003.

The real reason for nuking Iran, however, is none of the above. It was spelled out with surprising candor in the Pentagon draft document "Doctrine for Joint Nuclear Operations" [.pdf] as one of several possible reasons geographic combatant commanders may request presidential approval for use of nuclear weapons:

"To demonstrate U.S. intent and capability to use nuclear weapons to deter adversary use of WMD."

Yes, you read it right: The U.S. is prepared to break a 60-year-old taboo on the use of nuclear weapons against non-nuclear countries – not because the survival of the country is at stake, not because the lives of many Americans or allies are at stake – just to demonstrate that it can do it.

The U.S. has maintained for some time now that it reserves the right to respond with nuclear weapons to attacks or intended attacks with WMD, and that it intends to use nuclear weapons to destroy underground enemy facilities. It is argued that such statements have deterrent value, and that maintaining ambiguity as to what might trigger a U.S. nuclear attack deters countries from pursuing military initiatives that are contrary to U.S. interests.

Nonsense. Those statements have no deterrent value because no one in his or her right mind would believe that the greatest democracy in the world would do such a thing.

Unless the U.S. demonstrates, by actually doing it once, that it is indeed prepared to do so.

How do you create the conditions to perform such a demonstration and avoid immediate universal condemnation?

You declare Iran to be the second member of the "axis of evil."

You start a "global war on terror."

You invade the first member of the axis (Iraq) and put 150,000 U.S. troops at the doorstep of the second member, in harm's way – not enough troops to invade Iran, nor to prevent an Iranian invasion of Iraq after Iran is attacked.

You strike Iran's facilities, using conventional and nuclear bombs, to deter Iran from retaliating with missiles with chemical warheads and from invading Iraq, thereby saving the lives of 150,000 American soldiers.

You argue that Iran's chemical and nuclear facilities had to be destroyed to prevent terrorists using weapons from those facilities to attack the U.S. (Never mind that the nuclear facilities were just nuclear reactors, not nuclear weapons).

You get Israel to pull the trigger, i.e., bomb some Iranian installations (as it did in Iraq at Osirak) to provoke an Iranian response.

Now enter the world after the U.S. "demo," according to U.S. planners:

There will be no doubt that U.S. statements on the use of nuclear weapons will have deterrent value.

The Nuclear Nonproliferation Treaty will be amended to prohibit uranium-enrichment for all countries that do not do it already; violators will be nuked.

North Korea will be forced to disarm under the now real and credible threat of massive U.S. nuclear attack.

Any country suspected of pursuing nuclear weapons or any other military capability that could threaten the U.S. or its allies will be nuked.

Russia, China, and all other nuclear countries will eventually be forced to disarm under the threat of massive U.S. nuclear attack.

However, the real world does not always follow the script envisioned by U.S. planners, as the Iraq experience illustrates. So here is a more likely "post-demo" scenario:

Many non-nuclear countries, including those currently friendly to the U.S., will rush to develop a nuclear deterrent, and many will succeed.

Terrorist groups sympathetic to Iran will do their utmost to retaliate in-kind against the U.S., and eventually will succeed.

With the taboo against the use of nuclear weapons broken, use of them by other countries will follow in various regional conflicts, and subsequent escalation will lead to global nuclear war.

Bye-bye world, including the United States of America.