Iran dumps U.S. dollar for oil trades - CNN.com: "Iran has dramatically reduced dependence on the dollar over the past year in the face of increasing U.S. pressure on its financial system and the fall in the value of the American currency."
Here is another reason why unilateralism and tough-guy diplomacy doesn't work. It's the economy, stupid. The U.S. is/was powerful because its currency and economy were strong. The world does not have to work with us if they don't want to. When they stop, it gets ugly for us.