The conflict known since 1945 as the “cold war” was one of those titanic struggles between two great powers striving for hegemony that date back to the Greek-Persian confrontation in the 5th century b.c.e. and that recurred periodically thereafter. Notable instances included the Peloponnesian war, Rome’s struggles with Carthage three centuries later, the clashes of Christian Europe with Islam, the Hundred-Years war between England and France, and so on until modern times. Invariably, these conflicts took the form of armed clashes that, thanks to advances in weapons technology, claimed ever more victims. The invention of nuclear weapons in the mid-20th...