Assessments of al Qaida in Afghanistan in 2001 were accurate.
McCain signed the Report of the Commission on Intelligence on WMDs:
Al-Qa'ida in Afghanistan: Summary & Findings
The Commission compared the Intelligence Community's assessment of chemical, biological, radiological, and nuclear weapons in Afghanistan before and after Operation Enduring Freedom, the U.S.-led invasion of October 2001. We believe that the Intelligence Community correctly assessed al-Qa'ida's limited ability to use these weapons to inflict mass casualties. However, the war in Afghanistan and its aftermath revealed important new information about the level and direction of chemical, biological, and nuclear research and development that was underway. Specifically, we found that:
The Intelligence Community concluded that at the time of the commencement of the war in Afghanistan, al-Qa'ida's biological weapons program was both more advanced and more sophisticated than analysts had previously assessed;
Analytic judgments regarding al-Qa'ida's chemical weapons capabilities did not change significantly as a result of the war;
The Community appears to have been correct in its assessment of the low probability that al-Qa'ida had built a nuclear device or obtained sufficient material for a nuclear weapon. However, the war in Afghanistan brought to light detailed and revealing information about the direction and progress of al-Qa'ida's radiological and nuclear ambitions;
Intelligence gaps prior to the war in Afghanistan prevented the Intelligence Community from being able to assess with much certainty the extent or specific nature of al-Qa'ida's weapons of mass destruction capabilities;
Analysis of al-Qa'ida's potential development of weapons of mass destruction in Afghanistan did not benefit from leveraging different analytic disciplines; and
Analysts writing on al-Qa'ida's potential weapons of mass destruction efforts in Afghanistan did not adequately or explicitly state the basis...