He didn't think that was what circumstances required.
But circumstances changed on 9-11.
Let's stop with that silly, tired old crap. The upper ranks of the U.S. Department of Defense under the Bush administration -- long before 9/11 -- were filled with people who had been publicly advocating a U.S. military campaign in Iraq for years. They were not terrorism experts, they were not specialists in Cold War diplomacy, or relations between India and Pakistan, or in the dynamics of Latin America or sub-Saharan Africa. They were policy wonks who specialized in Middle Eastern affairs specifically with regard to U.S. military intervention for the purpose of "nation-building." That's exactly why they were there.
September 11th simply provided the Bush administration with the political support it needed to do something it had every intention of doing anyway.