The US government is considering reopening Pennsylvania Avenue in front of the White House, which had been closed because of security concerns. But counterterrorism “tsar” Richard Clarke warns National Security Adviser Rice that terrorists could easily drive a truck bomb, which he calls their “weapon of choice,” right into the White House. While discussing this, Clarke tells Rice that he thinks there are terrorist cells within the US, including al-Qaeda cells. [9/11 Commission, 7/24/2004, pp. 255]