Of the multiple international crises bubbling away in the world's various trouble spots, potentially the most dangerous is the spike in tensions between India and Pakistan. The reason is simple: It could cross the threshold to become a nuclear war. Conventional wars can kill large numbers of soldiers and civilians of the conflict parties but leave others largely untouched. By contrast, if India and Pakistan fought a nuclear war using only a fraction of their estimated 230 nuclear warheads, it could leave up to 2 billion people dead around the world through direct casualties, blast, heat, radiation and nuclear winter effects on global crop production and food distribution networks.

Because the costs of a nuclear war would be catastrophic, it is inconceivable that either government would pursue a deliberate strategy of courting a direct military confrontation. Yet arms control analysts have long identified the subcontinent as among the likeliest of global nuclear flashpoints.

How then might they end up fighting a nuclear war? There are several pathways through miscalculations, rogue launches, misinformation and jihadi provocations. The backdrop to these unintended and unwanted pathways to a nuclear war is the state of extreme tension in their relations where minor incidents can quickly spin out of the ability of either government to control.