I didn't claim it to be the only justification he gave for going. But it was one of the primary reasons he gave. He would have never gotten the support of the people in the country if he said we were only after older weapons that he had 20 years ago.
In October 2002, President Bush gave a speech in Cincinnati and spoke about the imminent threat Iraq posed to the U.S. because of the country's alleged ties with al-Qaeda and its endless supply of chemical and biological weapons:
"Surveillance photos reveal that the (Iraqi) regime is rebuilding facilities that it had used to produce chemical and biological weapons," Bush said. "Iraq possesses ballistic missiles with a likely range of hundreds of miles – far enough to strike Saudi Arabia, Israel, Turkey, and other nations – in a region where more than 135,000 American civilians and service members live and work. We've also discovered through intelligence that Iraq has a growing fleet of manned and unmanned aerial vehicles that could be used to disperse chemical or biological weapons across broad areas. We're concerned that Iraq is exploring ways of using these UAVs for missions targeting the United States. And, of course, sophisticated delivery systems aren't required for a chemical or biological attack; all that might be required are a small container and one terrorist or Iraqi intelligence operative to deliver it."