Senator Dick Lugar is a conservative Republican from Indiana but he's right on the money with this observation.
Dick Lugar 2006 - Fuel Freedom
"Our military has to secure shipping lanes, infrastructure and other access to oil , which conservative estimate place at $50 billion per year in the Middle East; and ... Economically, oil imports account for one-third of our trade deficit and were the primary driver of inflation in 2005."
And that's without the current estimated tally of $1.2 trillion on the current war in Iraq with the meter still running at something like $6-7 billion per month with no end in sight. One Nobel Prize winner in economics, Joseph Stiglitz, is saying it's already up to $2 trillion depending on what you count. Add in our comparatively small financial contribution in Gulf War I and you start looking at some pretty impressive numbers.
The NY Times made a graphic that gives a sense of the comparative magnitude.
"Putting the Annual Cost of War in Perspective" - NY Times
I've often wondered, by comparison, how much it would have cost to completely convert the USA to high efficiency energy technologies and renewable energy systems. I'm thinking it's probably pretty close to, if not already over, that level.
Fortunately, these wars were and are not about oil so this is just another random thought experiment on my part. Right.