A decent overview of the Iranian-Saudi cold war and how it is exacerbating post-Arab Spring instability in the region. I would add that a significant contributor to the tensions between the two has been Tehran’s desire to maintain a deterrent capacity vis-a-vis the US (and to a lesser extent Israel) through its relationship with groups like Hezbollah and Hamas. The competition then, can more accurately be described as three sided: Tehran-Riyadh-Washington. This triangle has been bent out of shape, so to speak, by the US-Iranian nuclear negotiation process and their collaboration in Iraq. It will be interesting to see what happens to the triangle if the negotiations between Iran and the US produce a deal.