After two oil tankers were attacked in the Gulf of Oman earlier this month, a threat of a US-Iran war has become a growing threat. On paper, the US can overwhelm Iran’s military forces easily. But if it comes to war, paper is not where it will be fought. While Iran’s defence facilities in the land, sea and air are no match to the Americans, Tehran has options and geography matters, given its strategic location and proximity to US bases. The huge added danger is that both sides have no direct line of communication, as Tim Marshall explains from <em>The National</em>'s London bureau Watch the latest edition of Sightline above.