From the field of GOP Presidential hopefuls, at least one of them understands the most basic fact about successful diplomacy:
The policy of the United States of America should be very, very clear that we will use any option we believe is in our best interest to stop them from becoming a nuclear power, and that we’re not going to allow that to happen…
…there is a better chance that we will never have to use military options in dealing with it.
Diplomacy is international politics and war is international politics by other means. To be effective, diplomacy must carry the inherent promise of those other means or the other party has no incentive to negotiate. Of course, leaving no option off the table also means leaving plenty of carrots on the table to go with the sticks, but in dealing with a rogue nation like Iran, a President must understand what Giuliani clearly does – diplomacy without teeth is doomed to fail.