LONDON -- As the military operation in Iraq rolls forward, those who still have doubts about the project -- and there are many -- have started to focus on all the catastrophes that could lie ahead, however speedy the campaign.

The long catalog of possible disasters includes millions of refugees, Iraq falling apart, Turks and Kurds turning on each other in renewed ferocity, a further destabilized Arab world, more frenzied anti-Americanism and terrorism, world oil-supply disruption, the United Nations undermined, European unity splintered, and the Atlantic Alliance more divided.

Pessimism and caution are probably healthy; it is wise to prepare for the worst. Yet they can be overdone. Alongside all the dangers are also opportunities that should at least be considered when weighing up the whole undertaking.