Imagine, for a moment, that the Iranian government announces it has developed a nuclear bomb and threatens to use it on Israel. The United States reacts with the threat of military intervention, as it did in 1991 and 2003 in Iraq. Iran signals that it will not tolerate a third Gulf war and looks for allies. American forces mass to enter Iran, which orders national mobilisation. Russia, China and North Korea express their support for Iran, and Washington expands its intervention force, bringing in a British contingent. Russia enters the game, raising the stakes in the expectation that the West...