And where was Clinton touring? The Mmiddle East, which has more than its fair share of military backed Oligarchies/dictatorships. And which Middle Eastern nation has nuclear capability, and has not disguised its willingness to use it - Israel?
America has real influence and could use it, Obama has failed so to do in any meaningful way.
When talking about whether sanctions can work look at Libya and South Africa as examples where they had a real impact in transforming the way these regimes dealt with the outside world. Sanctions were instrumental in transforming these regimes internally too. Iran even now does not produce enough petrol, so yes they can work- given time. Time may also strengthen the opposition.
David