BAGHDAD - Warning sirens wail and within seconds rockets and mortars strike sometimes one or two, other times 10 or more. The Green Zone is again a prime target as American and British diplomats, Iraqi politicians, contractors and others struggle to go about their business always aware that any time they are outside the most fortified buildings there is a chance to be injured or killed. The danger has temporarily reshaped life: Green Zone traffic is minimal, few people venture out on the streets and security precautions always high have been boosted. Many diplomats and others...