different from their own. If they ever run into trouble, they are instructed to call the mission. (If they did not, they could expect Saudi officials to call them.) Based on reporting by the FBI, US intelligence analysts believed the cultural center also served as a base for undercover Saudi intelligence officers who kept tabs on the growing numbers of students in the United States.

While Saudi diplomatic activity was monitored by the FBI as part of its routine counterintelligence efforts, Saudi intelligence officers seemed to focus on what they considered misconduct by their own citizens — advocacy of Islamist radicalism, criticism of the kingdom or other "political" activity.

But the ICE analysts learned that the Saudi operatives would also intervene when a student ran into legal trouble. "The initialinvestigation. "There were enough cases to constitute a pattern that rose to our attention, but there weren't enough to generate the interest level for a full-fledged investigation," the former senior official said. "Not to mention the diplomatic sensitivities."

Those sensitivities had risen sharply after 9/11. While the immigration authorities tightened their screening of Arab and other visitors after the attacks, the FBI stepped up its scrutiny of Saudis in the United States. Concerned about apparent ties between al-Qaida and the Saudi elite, the FBI created two new units in Washington that brought together counterterrorism and counterintelligence agents to track the possible Saudi threat.

At an April 2005 meeting at the Texas ranch of President George W. Bush, Crown Prince Abdullah, who was already the de facto Saudi monarch, made a