If the United States goes to war with Iraq, President Bush believes it must happen in a three-month window between mid-November and mid-February, according to high-level administration sources. While there are many reasons not to go to war, one big reason it has not happened is that the timing is not right. Bush wants to wait as long as he can to see if his sanctions will pinch Iraq into submission. The Central Intelligence Agency is preparing an estimate of the sanctions' effect and is expected to finish by mid-November.

Bush also needs more time to complete the military buildup, which has taken a month longer than originally planned. The troops will be in place when the window of opportunity opens.

White House sources explained to us why that three months is as ideal a period as Bush will get in the Persian Gulf. The weather is best between now and mid-February. After that comes "khamsin," so called for the 50 days or so of blinding sandstorms. Visibility is poor and even spy satellites are stymied. (If the United States begins the war, it will most likely happen on a moonless night when U.S. military strategists say their night-vision equipment will give them their best advantage.)

Any war must be over by March, which begins the month-long Moslem observance of Ramadan. The holy days celebrate Mohammed's receipt of the first revelation of the Koran. Moslems spend the days praying and reading the Koran.

If Ramadan comes and goes with U.S. troops still in Saudi Arabia, the Saudis definitely will want the foreigners out by June. That is the time of the "hadj" or the holy pilgrimage to Mecca. Every Moslem wants to go at least once in a lifetime, and every year hundreds of thousands travel to Saudi Arabia. No non-believers are allowed near Mecca. The hadj would be no time for Americans to disrupt the sacred rites of the Moslems. In 1979, the mere rumor that Americans instigated riots during the hadj caused a mob to set fire to the U.S. Embassy in Pakistan. Two people died in the fire.

The longer Bush waits, the stronger Iraqi defensive positions become. More than 2,000 Iraqi tanks are dug in behind sand barriers, barbed wire, land mines and napalm mines. The Iraqis hope their fortifications will cause so many quick U.S. casualties that the American people will demand withdrawal.

And the longer Bush waits, the more Kuwait is pillaged and decimated by Iraqi troops. Some intelligence estimates indicate that already as many as two-thirds of the Kuwaitis have been moved to Iraq. They are being replaced by a migration of thousands of Iraqis looking for a higher standard of living.

The morale of U.S. troops erodes every day they spend waiting. Pentagon reports say they are already losing their fighting edge.

The world alliance against Saddam Hussein also is eroding. Bush knows that the longer he waits, the more likely it is that some of those allies will wash their hands of the mess.

Finally, American support for war is diminishing, and along with it, Bush's popularity. The longer he waits to attack, the less support he will have for that attack when -- and if -- it happens.