Iranian officials say they are stepping up attacks on commercial vessels near the Strait of Hormuz and plan to expand their range. The strait is a vital route for global energy shipments. Disrupting maritime traffic drives up oil shipping and insurance costs, making it harder for oil prices to come down. Iran’s calculation is straightforward: keep oil prices high so Americans spend more at the gas pump, fuel voter dissatisfaction with Trump, and influence the U.S. midterm elections in November.

Little Iran—damn it, damn it—it’s going straight for Trump’s Achilles’ heel. Trump is in a tough spot now: if he doesn’t strike, Iran will keep attacking ships and oil prices will stay high; if he does strike, he could provoke an even larger retaliation and drive prices higher still. This time, Trump is learning what it means to be caught between a rock and a hard place.