You don't just "divert" multiple million barrel per day pipelines,

The pipelines are already there, check a map with oil infrastructure on it. All of the pipeline run right down towards the straights of Hormuz. So all you have to do, is protect what you have.. Tall order..

In response to the fact that Iraqi oil is not up to pre-war levels. You have to remember that Iraq's oil infrastructure was completely decimated before the war even started. 10 years of neglect and mismanagement guaranteed that we wouldn't see significant oil from Iraq for 5 plus years.

Robert NW Ohio

Prior to the invasion Iraq was pumping over 2.5 mbpd. In the three years since, in spite of the termination of sanctions, vast amounts of money being thrown at remediation and infrastructure improvements, the daily output is on a one-way descent towards oblivion. Currently Iraq is pumping about 1.5 mbpd - the principal reason for the steady collapse in output is the fact that there have been over 300 attacks on oil infrastructure, per IAGS figures; that's roughly 2 per week, every week. On top of that there are attacks on the electrical infrastructure which the oil infrastructure depends on. There will be significant improvement in Iraq's ability to produce oil until the insurgency ends - which will not happen, de minimis, until the US occupation ends.

Invading Iraq has been a disaster for oil output; invadind Iran would lead to the same outcome.