BEIRUT -- Such a spectacular al-Qaeda-style exploit might have come as no great surprise to moderate Saudi Islamists familiar with the thinking of the extremists in their midst. The Iraq war brought anti-American sentiments in the kingdom to new heights and increased the determination of militants to give expression to this feeling in violent, jihadist deeds.

"They are a volcano waiting to explode," said Saudi Muhsin al-Awaji in an interview in Riyadh during the war's final days. "I fear that they will strike not just at Americans and British but at Westerners in general."

This fear was certainly shared by the kingdom's vast expatriate community. They were confining themselves to their residential compounds, taking taxis rather than their own cars when they did venture out. Favored weekend haunts, like the old souks in downtown Riyadh, were almost deserted.