A now easily-referenced online source adds credence to claims by author and researcher Peter Lance that the US intelligence community had prior knowledge of a 9/11-style attack, if not the 9/11 plot itself, as far back as 1995.

While investigating the contents of a computer that belonged to Ramzi Yousef, data retriever Rafael M. Garcia, [under the aegis of the Philippine 'National Bureau of Investigation' (NBI)], discovered;

...another document that discussed a second alternative to crash the 11 planes into selected targets in the United States instead of just blowing them up in the air. These included the CIA headquarters in Langley, Virginia; the World Trade Center in New York; the Sears Tower in Chicago; the TransAmerica Tower in San Francisco; and the White House in Washington, DC.
This document surfaced after Garcia had already discovered various other plots on Yousef's computer, including the now infamous, Project Bojinka.

The FBI used the Bojinka information in Yousef's terrorism trial in 1996, but left out any mention of the plane-crashing alternative that specifically targets the World Trade Center. Lance claims that Philippine authorities handed the information over to the US, but it was never followed up.

Garcia says,

I submitted my findings to NBI officials, who most certainly turned over the report (and the computer) either to then Senior Superintendent Avelino Razon of the PNP or to Bob Heafner of the FBI.
The article was initially referenced by Nafeez Ahmed in his book, The War on Freedom. The online version of the article was recently found by 9/11 researcher, Paul Thompson, while updating the 'Operation Bojinka' section of his encyclopedic Terror Timeline.

Peter Lance's newest book, COVER-UP: What the Government is Still Hiding About the War on Terror carries his research further, irretrievably shredding the impartiality and credibility of the 9/11 Commission's Final Report.