The C.I.A. knew that high-level Qaeda operatives had held a meeting in Malaysia in January 2000, and, later, that two of them had entered the United States. Both men turned out to be part of the team that hijacked the planes on Sept. 11. The C.I.A. failed to inform agencies like the F.B.I. -- which might have been able to locate the men and break up the plot -- until late in the summer of 2001. More →