Some critics of President Bush's desire to launch a pre-emptive military strike against Iraqi dictator Saddam Hussein are troubled by the fact that it would be … well, pre-emptive.

They want the president to wait until Saddam commits another act of aggression before the United States takes action. But how much more aggressive does he have to become?

Saddam Hussein is a serial mass murderer responsible for the deaths of thousands of Iraqis, up to half a million Iranians in a bloody war, and unknown numbers of Kuwaitis, other Arabs, Israelis and Americans. He has invaded Iran and Kuwait. He has attacked Israel, Saudi Arabia and Bahrain with missiles. He poses a growing threat to our national interests and to the stability of the Middle East -- which, considering the region's volatility, is really saying something.

The Bush administration must de-fang Saddam soon, because his regime grows more dangerous by the day. United Nations' weapons experts estimate he has stockpiled more than 600 metric tons of chemical agents such as mustard gas and nerve gas. U.S. intelligence officials, meanwhile, say he has successfully rebuilt his secret programs to develop even more deadly biological and nuclear weapons.

And we know he's willing to use them. Saddam unleashed chemical weapons against Iran in his 1980-1988 war and even against his own people: In 1988, up to 5,000 Iraqi Kurds opposed to Saddam's government were gassed in the town of Halabja. Any leader capable of using such horrific weapons against his own people wouldn't think twice about using them against his neighbors -- or against the United States.

The only way to rid Iraq of these prohibited weapons is to rid Iraq of Saddam's dangerous regime. U.N. arms inspectors cannot do the job, because they cannot inspect what is kept hidden from them. The U.N. inspection regime was based on the faulty assumption that Saddam would cooperate in order to lift the U.N. economic sanctions. But he "cooperated" by letting the inspectors search for needles in empty haystacks. The minute inspectors wandered near anything incriminating, the Iraqis blocked them.

In this manner Iraq thwarted the efforts of U.N. inspectors to disarm Iraq before kicking them out in 1998. Since then, Saddam has had free rein to rebuild his weapons of mass destruction. German intelligence and a defector from Saddam's nuclear program estimate that Iraq is three years away from acquiring a nuclear weapon.

In the meantime, Saddam's possession of chemical and biological weapons of mass destruction, his thirst for vengeance for his defeat in the 1991 Gulf War, and his longstanding support for international terrorists make him extremely dangerous.

After the Sept. 11 terrorist attacks, the United States would be foolhardy if it failed to make every effort to prevent these weapons from being transferred to Iraq's terrorist surrogates. Conventional deterrence didn't prevent Saddam from trying to assassinate President Bush's father in 1993 in Kuwait, and it can't be relied on to stave off future aggression by this reckless dictator.

Some opponents of U.S. military action against Iraq claim it would undermine Arab-Israeli peace efforts and the war against international terrorism. They have it exactly backward. Saddam's regime violently opposes peace with Israel and fuels the current violence by paying the families of Palestinian bombers up to $25,000. The peace process lurched forward in 1993 only after Iraq had been cut down to size in 1991 and was isolated diplomatically.

And, far from being a diversion, a campaign for "regime change" in Iraq is a necessary step in fighting the war against terrorism. There can be no real victory over terrorism as long as Hussein's regime, one of the chief state sponsors of terrorism, remains in power.

The Bush administration is not trying to pick a fight. Rather, it is Iraq that has forced a confrontation with the United States. By blocking U.N. arms inspections, Iraq has violated the 1991 cease-fire agreement that ended the Gulf War and technically entered a state of war with the United States.

Washington should not back down from Saddam's deadly challenge. Although the risks of confronting Iraq are considerable, the risks of inaction are even greater. Failing to deal with Iraq now will only postpone the crisis. And confronting a nuclear-armed Iraq later will be much more dangerous.

James A. Phillips is a research fellow specializing in Middle Eastern affairs in the Davis Institute for International Studies at The Heritage Foundation.