U.S. Army intelligence had detected 9/11 terrorists year before, says officer

A year before the 9/11 attacks, through data mining a U.S. Army intelligence group had identified two terrorist cells, including Mohammed Atta and three other 9/11 hijackers. Lieutenant Colonel Anthony Shaffer, a liaison officer of a unit called Able Danger, has spoken on the topic. By analysis of non-military data, several of the terrorists with direct links to top Al-Qaeda leadership were identified.

Able Danger also used publicly available information from government immigration agencies.

Description on CNN of the technology involved:

SHAFFER: "...Land Information Warfare Activity, LIWA, at Fort Belvoir, Virginia, an Army unit ... this targeting exercise of al Qaeda. What the LIWA did -- and it was their ability to go through massive amounts of open-source data, 2.5 terabytes, and look for patterns that related to previously-known terrorists. It was that information then which popped up...

S. O'BRIEN: So, by trolling the Internet and LexisNexis, things like that, I think that's what you mean by open source data? Am I right about that?

SHAFFER: Open source -- anything that's not a classified database. We're talking about commercial databases, financial databases. Anything that's out there that relates to the real world."

On the Sean Hannity Show Wednesday, Shaffer said there were direct links to top Al-Qaeda leaders. He repeated that on Thursday.