I found this history of the Iran-Iraq war very enlightening about the real reasons behind a war against Iraq. I will summarize it for you: US control over the oil in the Middle East.
The control is not required because a need on the Middle East oil, but because Japan and Europe are highly dependent on it. You want *your* companies profiting from that oil, and not someone else.
It also explains why Britain wants to get some piece of the action. In fact, they have always wanted to get a piece of the action.