MANY WASHINGTONIANS, frightened after several days of new threats and increased talk of war, wonder whether the nation is foolishly poking a hornet's nest. Why must the United States attack Saddam Hussein if that will only anger much of the Islamic world? Don't the latest threats from Osama bin Laden or his proxy prove the recklessness of America's aggressive stance? Such questions reflect an understandable and justified anxiety. But they also reflect a mistaken view of the broader war in which the United States finds itself, through no choice of its own.

For more than two decades, the country tried a strategy of not poking the hornet's nest -- a strategy of accommodation, half-measures and wishful thinking. In the 1980s the United States sold arms to the Iranian government that had kidnapped American citizens and withdrew its Marines from Lebanon after a suicide bomber destroyed their barracks. In the 1990s a warlord's attacks prompted America to retreat from Somalia, and a fundamentalist government in Afghanistan allowed thousands of Islamist extremists to learn to kill Americans while America, knowing what was happening, did not interfere. Terrorists bombed the World Trade Center in New York in 1993, a U.S. military dormitory in Saudi Arabia in 1996, two American embassies in Africa in 1998, the USS Cole in 2000 -- and each time America responded feebly or not at all. During the past decade the United States vowed many times to disarm Saddam Hussein, who made no secret of his hatred and enmity toward the United States; but when the Iraqi dictator resisted, the United States chose to abandon its vows rather than use the force that would have been needed to enforce them. In every case, the calculation, stated or unstated, was the same: Pay tribute, don't make trouble, and maybe nothing worse will happen.

In the ruins of Lower Manhattan in September 2001, most Americans saw evidence that this calculation was incorrect as well as craven. The nation's enemies would not be deterred or mollified by a gentle response; they would be emboldened. President Bush rightly concluded that the nation had to defend itself more vigilantly -- but also that no defense could succeed unless accompanied by an offensive against the terrorists and the states that sheltered them.

The resolve to disarm Saddam Hussein, finally, 12 years after the United Nations first insisted, grows inescapably from this new understanding. He shelters terrorists who have killed Americans and who would like to kill more. He owns large stocks of chemical and biological weapons and has considerable experience in their use. To allow him once again to outmaneuver the United Nations and continue his quest for nuclear weapons would subject Americans to unacceptable risks. It would also show other terrorist sponsors that, brave 9/11 rhetoric notwithstanding, they still have nothing to fear. The longer he remains unchallenged, the greater the risk.

Last week's orange alert and this week's al Qaeda tape remind the nation of real perils. The audiotape shows the Islamicists' willingness to set aside their disdain for Iraq's secular rule in the greater shared struggle against America. Al Qaeda does not need new pretexts to launch new attacks, but it may seek to time attacks to coincide with American war or preparations for it. Americans are right to prepare as best they can and to insist that the government do more to inform and defend -- and they are right to be nervous.

Yet they would be wrong to let fear cloud their judgment. A war with Iraq, if it comes to that, won't automatically make the world less dangerous; much will depend on America's commitment to help Iraq rebuild and reform. But what is certain is that the attacks will not stop, nor the dangers fade, if the United States backs down in the face of threats. That approach has been tried.