Even serious analysts consider Iran as capable to close the Straits of Hormuz, at least for a brief time. The truth is that a couple burning mega-tankers and myriads of magnetic mines on the bottom of the Straights would do.
They are probably already there, and just waiting to be activated.
Unlike like military ships, the tankers are not build with demagnetised hauls. The Straights are the major route for not only for Iranian oil, but mostly Iraqi, Saudi, Kuwait and UAEs,- imagine the consequences.