REALCLEARPOLITICS points to a passage in this Washington Post story:

The Saudi official said there were at least three al Qaeda cells with about 50 hard-core operatives in the kingdom before the bombings. He acknowledged that there was a much wider circle of sympathizers, and U.S. officials broadly agreed with his analysis.

“We don’t believe there are tens of thousands of active al Qaeda members here, but we believe the al Qaeda presence is more than a single cell or two cells,” a senior U.S. official told reporters today.

As RCP notes, if that’s the scope of the problem, then it’s not much of a problem. But is it?