I agree with Lilo on being against another unilaterally launched, unprovoked war Baghdad 2.0.

But in regards to shutting down the Straits, which is another matter completely and potential military scenario all together...I would suggest not to back down, not one bit. If they're really (stupidly) going through with it, its technically an illegal act of war to shut down global trade and commercial sea routes in International friendly waters. Nevermind the economical ramifications as Lilo already pointed out.

But that aside, push the limits of their resolve, see how willing they are to enforce it. Don't open fire, let those assholes make the first move. Let them hang themselves. I say "stupidly" on their part because if one Iranian ship fires at one American ship or plane or submarine, the inevitable anger that will arise from the American domestic front will indeed bring upon "regime change." (I'm pretty certain many Americans are wet-dreaming such a scenario as we're speaking.)

Tehran is banking on American public's apathy for another war, which they're right. Ron Paul is the only GOP candidate against war w/ Iran, yet he's got the most military campaign donors of all the candidates in the field.

But push comes to our naval shove, Tehran will pussy out because they don't want to step on Superman's cape. Talk is cheap, action is expensive.