But if the realistic worst-case scenario for Saddam building a bomb is three years—with the opportunity for us to inflict Osirak-type setbacks along the way—why must we invade Iraq right now? Certainly, there are risks to waiting. We could misjudge the situation, or Saddam could get lucky on the black market. And of course, as long as Saddam remains in power, the Iraqi people will suffer mightily. But we have to weigh the risks of delay against the hazards of acting. The Taliban model might not hold. A ground invasion could cost many American lives or fracture the anti-terror coalition. Perhaps most alarmingly, a U.S. invasion could provoke Saddam to use biological and chemical weapons that he already has against Israel, Kuwait, or U.S. interests. Saddam is currently deterred from using weapons of mass destruction by the expectation of retaliation. But as Steve Chapman points out, this deterrent effect breaks down once we signal our intention to finish him off.
For the United States, there are also benefits to waiting. If can we hold off attacking Iraq for a time—while keeping close tabs on Saddam's nuclear program—we might be the ones to get lucky. Saddam Hussein is 64 years old. Between now and making a bomb, he could succumb to natural causes, or unnatural ones like a coup or a Mossad bullet. As he gets older, Saddam might even realize, in the way Muammar Qaddafi seems to have done, that whatever his ambitions, menacing the United States is a suicidal tactic. But if we don't get luck in any of these ways, we can still send in the Marines.