They are waving their Willy....and only threatening to hold a drill....as even the Mullahs know attempting to close the Straits of Hormuz to shipping traffic would kick off such a retalitory response that even their eyes would water!
They might use harrassment tactics...sea mines...surface attack by small boats....but a full fledged blocking of the shipping lane....not in their life time.
Well...it would be just prior to the quick end of their life time anyway!