Profit from endless weapons sales, profit from cheap oil, and keep the dollar strong by only selling the oil for the dollar. 3 birds with one stone.
http://www.theguardian.com/business/2003/feb/16/iraq.theeuro
And now here we are, oil is cheaper than it has been since the invasion of Iraq in 2003 and the dollar is more valuable than it has been in decades (relative to other currencies) all the while the instability in the middle east continues to increase.
http://www.macrotrends.net/1369/crude-oil-price-history-char...
"The war is not meant to be won, it is meant to be continuous."