Why are we in Iraq? This makes the most sense of any explanation I have read. All the 9/11 hijackers and Bin Laden were Saudi's, yet attacking the worlds main supplier of oil was unacceptable. So we have incircled them.
"By then it had identified the jihadist campaign as "a Saudi problem". Most of the September 11 suicide attackers had been Saudis. Bin Laden was a Saudi. Saudi money trails were everywhere. An invasion of Saudi Arabia presented the tactical problem of waging war against a country of vast area and the strategic one of disrupting the world's oil supplies.
The Americans had established and then strengthened a military presence in countries surrounding Saudi Arabia - Yemen, Oman, Qatar, Bahrain and Kuwait. Invasion of Iraq would complete the encirclement."
I have said all along the Iraq invasion was deeper than most thought, and was a strategic move for the future. This is a good review of the reasons for going into Iraq. Read it all at ProfessorBainbridge.com: Why Iraq?">Professor Bainbridge.