Like Franklin Roosevelt, who tried to starve Japan into submission by halting its imports of oil, Trump seems intent on trying to bludgeon Iran into submission by preventing it from exporting any crude. The problem is that the Iranians aren’t cracking. Instead, they are likely to double-down. Already they are threatening to shut down the Strait of Hormuz. Trump will be in dire straits if Iran does that. A fifth of the world’s crude oil flows through it. The US military has positioned two carrier strike groups near Iran.