The Strait of Hormuz links the majority of the world’s people who live along the shores of Asia and East Africa to the heart of the Middle East. Long before the discovery of oil, it was the world’s carotid artery. Cut off the blood supply almost anywhere else and the world would adapt. Here, however, an interruption could be fatal: 90 percent of oil exported from the Gulf, about 20 percent of the world’s supply, passes through Hormuz.