conflict. certainly if it becomes a ground conflict that would be a dramatic escalation. when you consider the strategic location of yemen, right at the tip of the arabian peninsula. its coastline along some of the most important commerce shipping routes in the world. oil commerce routes. so, so far saudi arabia has been been carrying out what it describes as an effective air campaign. the houthi rebels backed by iran say they will not back down. and, richard, when you look at the problems that are going on in yemen, the problems that are going in in syria and in so many other countries in the middle east, and northern africa, the tentacles that you see in every one of these countries come from iran. reporter: there is a wider struggle for dominance in the middle east right now. between the sunni world, primarily saudi arabia and iran representing the shia world. you see that struggle playing out in syria, where sunni