Why did India and Pakistan carry out nuclear tests in 1998 and what are the consequences of their actions? This paper examines the complex domestic and international factors that persuaded each country to drop its long-standing nuclear ambiguity. It also unravels the repercussions of the tests, both for regional stability and for global non-proliferation regimes, and argues that the West needs a new approach if it is to deal with the nuclear dangers on the subcontinent.