Perhaps 9/11 allowed the bureaucracy to push its agenda, but it is very clear that it took Bush completely off his plan; Bush campaigned for a less activist foreign policy (which many criticized as being isolationist).
https://en.wikipedia.org/wiki/Project_for_the_New_American_C...
10 of 25 signing members of PNAC were high level bush administration workers. PNAC was explicitly neoconservative and most definitely wanted to be involved in more wars abroad.
It seems to me that just as the NBA is full of (some of) the tallest people in the country, the Congress and White House are full of the people who are most capable of believing whatever they have to at any given moment.
When that amount of money and power is at stake, there's no room for people who are earnest.
The rationale was that Hussein needed to be replaced. Iraq was too unstable and it might fall to Iran, which would upset the power balance in the middle east. I think Afghanistan was thrown in as an afterthought because, you know, "terrorists".
http://www.cnn.com/2004/ALLPOLITICS/01/10/oneill.bush/
> (CNN) -- The Bush administration began planning to use U.S. troops to invade Iraq within days after the former Texas governor entered the White House three years ago, former Treasury Secretary Paul O'Neill told CBS News' 60 Minutes.
> "From the very beginning, there was a conviction that Saddam Hussein was a bad person and that he needed to go," O'Neill told CBS, according to excerpts released Saturday by the network. "For me, the notion of pre-emption, that the U.S. has the unilateral right to do whatever we decide to do, is a really huge leap."
http://www.cbsnews.com/news/bush-sought-way-to-invade-iraq/
> He got briefing materials under this cover sheet. "There are memos. One of them marked, secret, says, 'Plan for post-Saddam Iraq,'" adds Suskind, who says that they discussed an occupation of Iraq in January and February of 2001
> Based on his interviews with O'Neill and several other officials at the meetings, Suskind writes that the planning envisioned peacekeeping troops, war crimes tribunals, and even divvying up Iraq's oil wealth.
For reference, the towers fell on Sept 11, 2001.
For the rationale my understanding mostly derives from various reddit threads (e.g. [1]), a friend who majored in criminology, and this fantastic overview of Iraq at Wait but Why [2].
[0] https://duckduckgo.com/?q=bush+iraq+invasion+before+9%2F11
[1] https://www.reddit.com/r/changemyview/comments/1lx1s7/oil_pl...
[2] http://waitbutwhy.com/2014/09/muhammad-isis-iraqs-full-story...
> The US Department of Defense had placed the final documents on Bush's desk (ready for him to sign) 48 hours prior to the fall of the first tower.
https://www.wsws.org/en/articles/2002/05/bush-m18.html
> From this standpoint, the most important of the week’s revelations was the report by NBC News that Bush had on his desk September 9—two days before the attacks on the World Trade Center and the Pentagon—a National Security Presidential Directive outlining in detail a worldwide campaign of military, diplomatic and intelligence action targeting Osama bin Laden and his Al Qaeda organization, including the delivery of an ultimatum to the Taliban regime in Afghanistan, backed by the threat of war.
UPDATE: Incidentally, my search led me to a Guardian article which claims that a plan to "escalate pressure on the Taliban to surrender Bin Laden to he US" had existed as far back as the Clinton administration. This is new to me.
http://www.theguardian.com/world/2004/mar/24/september11.usa...
0: http://rethink911.org/ 1: http://www.globalresearch.ca/twenty-six-things-about-the-isl...