I found this rather interesting.
The 911 Commission report documents a proposal made in 1999 to send a U-2 mission over Afghanistan to gather intelligence on where bin Laden was hiding (page 134). Mr. Clarke objected on the grounds that Pakistani intelligence would tip bin Laden off that the U.S. was planning a bombing mission. "Armed with this knowledge," the report quotes Mr. Clarke as saying, "old wily Usama will likely boogie to Baghdad."