First, the Trump administration is effectively pursuing a policy of regime change in the Islamic republic, hoping expanding sanctions will break the Iranian economy. Hours before Trump’s blast, Secretary of State Mike Pompeo gave a high-profile speech in California, proclaiming US support for protests against “hypocritical holy men.”

Second, Iran’s regime — the Supreme Leader and President Hassan Rouhani, forced into tougher rhetoric by hardliners — are issuing their own threat: to hinder the oil exports of other countries if Tehran’s sales are sharply reduced by US sanctions. That threat could include blocking the Strait of Hormuz at the top of the Gulf, a vital route for oil tankers.