The US response has also been remarkably restrained, so far, perhaps indicating a readiness to negotiate.
Translation into Farsi: weakness.
I think
WE Branch Fanatic's assessment is about as close to the money as anyone's likely to get. I agree they will try something far more subtle than blocking the straits to all traffic. However, the wild card is how much the recently-introduced sanctions will hurt them, or more particularly, how long they can bear them? (The Japanese situation after the oil sanctions in late 1941 again come to mind.)
Unless the new sanctions have changed the whole shootin' match (or time line), the one thing the Iranians want is to stall any US/NATO move until they have their nukes up and running - and about one nanosecond after that, "negotiations" take on a whole new meaning.
But let no one understate the importance of the November US elections and what they may 'force' the Obama administration to do to get Barry re-elected.