I can see no reason that conforms to an argument of logic, law, justice, or human compassion that could justify a unilateral attack upon Iraq.
Saddam Hussein is one dictator among many in the Middle East. Other dictators, such as those in Kuwait, Qatar, Saudi Arabia, the UAE, and so on, are US allies. Today, Iraq is a shadow of itself, and cannot be seriously compared to the Iraq of 1989, which enjoyed aid from the US government and chemical weapon components from US corporations.
US administrations have made it clear since the Persian Gulf War that they do not care about weapons inspections, but about removing Hussein from power. But, considering that the US instead proposes an "iron-fisted Iraqi junta" (that will take marching-orders from Washington) in Hussein's place shows the shallowness of its "concern" for the people of Iraq and the region.
Bush is exploiting the situation of Iraq-- where people have suffered incredibly under the murderous economic sanctions regime-- to draw attention away from his radical-conservative policies and economic scandals. Were the focus of the country instead upon the corruption of corporate influence in our democracy, such as the scandalous energy corporation Enron, we would see that not only are our politicians bought-and-sold, but that those very corporations are often the main motivations for US foreign policy.