“Security is strong,” Larssen said, “…unless there are people on the inside who are willing to work with terrorists.”

And, from earlier in the article:

“There are and have been Pakistani scientists or elements of the complex that have had sympathies and met with people who would be considered to be our enemies,” Zarate said.

The good news is that the percentage of Pakistanis who support Al Qaeda has declined dramatically in the past few years. Here are the most recent figures from Pew:

Al Qaeda: 25% favorable, 34% unfavorable, 41% don’t know
Taliban: 25% favorable, 33% unfavorable, 40% don’t know