But if we read this essay from Commentary Magazine, we can see that it may be an inaccurate claim the Senator is making.
Throughout his dramatic campaign to win his party’s nomination for the presidency, Senator Barack Obama has tended to ignore the specifics of policy in favor of the generalities of emotion, centering his appeal to voters on vague promises of “change” and “unity.” But on one issue, above all others, Obama has remained fixated from the campaign’s first moment, and that is the war in Iraq. By Obama’s own account, the consistency of his stand on this war demonstrates more than anything else that he, a one-term United States Senator who arrived in Washington in 2005 with no foreign-policy experience, after an uneventful eight-year stint in the Illinois state senate, possesses the wisdom, the clear-sightedness, and the judgment to assume the responsibilities of the nation’s commander-in-chief.
What follows is a lengthy but thorough article, as it chronicles the vacillating positions Obama has communicated on the war. It's what the enamored and mesmerized media types will not press him on. It's what the hypnotized inexperienced youth that eat up his every word do not want to read or hear.
Decision making is based on the information you have at the time. Sometimes, it's a crap shoot. It's certainly easy for any "Johnny come lately" to say: "If I would have been there, I would have voted no." It's easy to use hindsight as your basis of dissent, especially when their is no official public record of your stances. And Obama is getting away with doing this right now. He has a free pass to make his claim, without fear of being challenged.
But all of that is about to change, once he secures the nomination and must take on experienced people that know far more than him. It will come to a screeching halt when those that have a deeper understanding of the conditions in the world, get him onto specifics and off of the tired hope and change message.
Read this essay, if you are capable of making decisions for yourself (based on careful thought and deliberation). If you already have your mind made up, don't bother. You will be wasting your time.