Osama Bin Laden Evidence: Al Qaeda Considered 9/11 Anniversary Attack

The trove of evidence U.S. Navy SEALs recovered during their raid of Bin Laden's compound, which cost the al Qaeda leader his life, shows that al Qaeda remained fixated on so-called soft targets like transportation.

A new bulletin issued tonight by the FBI and the Department of Homeland Security and obtained by ABC News describes the terror organization's chilling desire to derail a train.

"As of February 2010, al-Qa'ida was allegedly contemplating conducting an operation against trains at an unspecified location in the United States on the 10th anniversary of September 11, 2001," the document reads, using an alternate spelling for bin Laden's terror group. "As one option, al-Qa'ida was looking into trying to tip a train by tampering with the rails so that the train would fall off the track at either a valley or a bridge."

"You can't guard hundreds of miles of track," said ABC News consultant and former White House counterterrorism advisor Richard Clarke. "And if they can get to one location that is not well guarded and put explosives on it or do something to cause the train to derail that's a lot easier than going after an aircraft."