On the recordSeptember 10, 2007
I can assure you, without going into the details, that we continue to make a major effort to find Osama bin Laden and Ayman al-Zawahiri, the No. 2 man. If any Senator wants to come to the Senate Intelligence Committee in Hart 219, we will be happy to brief them on the efforts made there. As far as the threat to the United States, the greatest threat to the United States from abroad is having al-Qaida establish a safe haven where they can recruit, have training facilities, issue command-and-control orders, and develop weapons of mass destruction. We have no better authorities than Osama bin Laden and Ayman al-Zawahiri that they still seek to establish that headquarters for their effort in Iraq because this is where they believe their caliphate should be headquartered.
Source
govinfo.gov