Between 2004 and the fifth anniversary of the September 11 attacks in 2006, mainstream coverage of the conspiracy theories increased. The U.S. government issued a formal analysis by the National Institute of Standards and Technology (NIST) of the collapse of the World Trade Center. To address the growing publicity of the theories, the State Department revised a webpage in 2006 to debunk them. A 2006 national security strategy paper declared that terrorism springs from "subcultures of conspiracy and misinformation," and that "terrorists recruit more effectively from populations whose information about the world is contaminated by falsehoods and corrupted by conspiracy theories. The distortions keep alive grievances and filter out facts that would challenge popular prejudices and self-serving propaganda." Al-Qaeda has repeatedly claimed responsibility for the attacks, with chief deputy Ayman al-Zawahiri accusing Shia Iran and Hezbollah of denigrating Sunni successes in hurting America by intentionally starting rumors that Israel carried out the attacks.