Iran would have big problems if it attempted to close the Strait of Hormuz, the only passage out of the Persian Gulf and into the Indian Ocean.

But that’s exactly what Iranian leaders threatened to do this week. Motivated by U.S. warnings that sanctions will be imposed on any nation that buys Iranian oil exports after Nov. 4, on Tuesday, President Hassan Rouhani said that the “[U.S. warning] has no meaning for Iranian oil not to be exported, while the region’s oil is exported.” On Thursday, Iranian Revolutionary Guard commander Ali Jafari declared that “either everyone or no one can use the Strait of Hormuz.”