How do you sanction a country like Iran?

Andrew Sullivan has been blogging about Iran juuuust a wee bit the past 48 hours.  Now he asks a question:

The Green Movement has strongly resisted all sanctions against Iran, and even more passionately opposes any military strikes. If Israel strikes, it will effectively kill the Iranian opposition movement, and set off a global wave of Jihadism which will kill many American soldiers and civilians. So how to respond to the Revolutionary Guards’ continuing and mounting brutality?

He also links to some useful Spencer Ackerman posts, which contains the following two points of interest:

1. Some leaders of the Green Movement are begining to think some targeted "smart" sanctions might be useful;
2. The Obama administration has been pulsing the system to figure out what the possible sanctions options are. 

What to do?  I think two big questions need  to be asked.  First, how are the sanctions supposed to work?  Is the idea to squeeze the elite coalition ruling Iran just hard enough to get the current leadership to cut a deal?  Or is the idea to cause enough discontent with the regime such that it collapses, and then a deal can be struck with the next regime?

The process by which sanctions are supposed to work matters.  If the hope is to still do business with the current regime, then targeted or "smart" sanctions make more sense.  They’re less likely to impact the broader Iranian population — though, like precision-guided munitions, there will always be collateral damage. 

If the goal is regime change, well, then broad-based sanctions might make more sense.  If these reports are any indication, then  it appears that the Khamenei regime is alienating an ever-larger swath of the population.  Obviously, the regime could try to use the prospect and implementation of broad-based sanctions as a way to rally around the flag.  If the regime’s popular support is badly eroding, however, and that erosion is partly explained by economic hardship, then you want sanctions to target a somewhat larger segment of the populace. 

Of course, as I’ve said before, this is all sophistry unless you get Iran’s major trading partners on board.  And my hunch is they won’t go for the "heavy" sanctions option.  This is a shame, because at this point, I think it’s the option that’s somewhat more likely to work.   

Let’s not kid ourselves, however:  we’re talking about policy options that will change the probabilities by a few percentage points either way.  There is no magic bullet — or bomb, for that matter — on this policy quiestion. 

Am I missing anything?