Just as the United States’s stark political divisions arguably were decisive in Trump’s withdrawal from the Obama-era JCPOA, Iran’s competing power centers were divided over the agreement. Those supporting limited compromises with West have been made to look foolish, giving ammunition to the hardline religious factions and their Revolutionary Guard Corps paramilitaries.

Thus, Tehran is now retaliating with a “maximum pressure” campaign of its own. Iran cannot use sanctions to punish America, but it can inflict economic pain by threatening the valuable shipping lanes running from Persian Gulf ports, through the straits of Hormuz, and into the Gulf of Oman.

During the Cold War, Soviet premier Nikita Kruschev famously said “[West] Berlin is the testicle of the West. When I want the West to scream, I squeeze on Berlin.” The Persian Gulf is Iran’s West Berlin.

One-third of all the world’s oil passes through Hormuz. Both the Gulf and the Straits are quite narrow—only twenty-one miles at the latter’s narrowest point—and shallow, with only one or two viable transit lanes through which large tankers can pass at parts. The north-eastern half of the Gulf coast is Iranian territory, meaning Iranian units can stage fast boats and long-range missile batteries for attacks at any point along that roughly 1,000-mile coastline.