This paper explains how Iran developed its nuclear programme to the point where it threatens to achieve a weapons capability within a short time frame, and analyses Western policy responses aimed at forestalling that capability. Key questions are addressed: will the world have to accept an Iranian uranium-enrichment programme, and does having a weapons capability mean having the Bomb? For nearly two decades, Western strategy on the Iran nuclear issue emphasised denial of supply. Since 2002, there has also been a demand-side dimension to the strategy, aimed at changing Iran's cost-be