|This cool graphic adds a sense of drama to the narrative|
And surprisingly, considering the rather uninspiring history of the use of economic sanctions, these appear to have worked. Iran has indicated that they are broadly prepared to negotiate limits to their nuclear enrichment program in exchange for a reduction in the sanctions regime. This would appear to be a clear cut victory for the world. It's the way these things are supposed to work - bring economic pressure to bear to punish behaviors agreed to be unacceptable, then reduce that pressure to reward steps toward compliance with demands. Any other approach would be irrational - to bring sanctions to bear to change behavior but then to offer no clear path towards getting those sanctions lifted would be pointless and cruel. No sovereign nation would agree to a set of external demands under coercive pressure without a corresponding agreement to reduce that pressure - there would simply be no reason for them to do so when the outcome would be no change to their conditions. To put it another way, a permanent and non-negotiable sanctions regime is not a method for changing behavior, but rather more an act of economic warfare intended to topple governments, and in spite of claims to the contrary should be seen in that light.
Despite the belligerent talk, no one short of some rather unpleasant pundits actually wants war with Iran. Iran would perhaps like to develop a nuclear weapon as a deterrent - while there is no active weapons program in Iran now, the civilian research program undeniably shortens the path to a 'breakout' capability - but it must be recognized that Iran has a powerful deterrent available today: Geography. The Strait of Hormuz is critical to providing about a quarter of the world's crude oil, and with production rates only slightly greater than consumption any disruption of this necessary shipping route will create shortages and drive the price to unprecedented heights, creating a global recession. No matter the reassuring platitudes uttered by the US Navy, it is well known that Iran can use its proximity to the Straits to wreck the economies of the US, Europe and Asia anytime they choose. This is without even considering the pent up forces that would be unleashed by a regional war - the festering Sunni vs. Shi'ite conflict in virtually every Gulf nation, the hatred for America and Israel, the plight of the Palestinians, Israeli and Pakistani nuclear weapons - you can be sure that nobody, not even the pathological Netanyahu really wants to find out how that all turns out.
So if starting a war isn't the goal, and the sanctions aren't being used to modify Iranian behavior despite the claims to that effect, what IS the agenda of the anti-Iran western governments? Well, I can't think of many outcomes from a one-way sanctions regime outside of regime change. And I think we if we look at how the sanctions process is being managed, in an atmosphere of constant threats of unprovoked attacks and an absolute unwillingness to take "yes" for an answer, the only possible intention is the collapse of the Iranian Theocracy. But short of open warfare, this certainly seems like the highest risk, lowest reward agenda that western governments could pursue. The uncertainty about how the current regime would collapse, how much chaos, violence and disruption would result, and who would take over the Iranian leadership is nearly limitless. It could be an even more hard-line Theocracy. It could be a military dictatorship under the generals of the Republican Guard. It might even be a more secular liberal democracy. But no matter what government takes power, in light of their own very recent history, they are almost certain to abrogate the NPT and build nuclear weapons. The current Iranian regime says nuclear weapons violate Islamic scriptural law. It's hard to imagine any follow-on government willing to continue this weapons policy considering the way they themselves came to power. Without the motivation of religious doctrine, all the incentives point the other way.
One of the better arguments against war (although not the best, which is that starting unprovoked aggressive wars is by its very nature evil, or even the second best, that a war of this magnitude in this specific place would wreck the global economy for years) is that it would, more than anything else, convince the Iranians to go all-out to develop a nuclear weapon. This same argument applies to coercive regime change, although that certainly appears to be the course the anti-Iranian west has chosen. From here, it looks part and parcel of a particular kind of growing ideological madness, a sense that negotiations and compromises are something to be avoided, that victory comes not from consensus or agreement, but only from the total destruction of one's adversary. Because if the west instead used the pressure generated by the sanctions to get incremental agreements from the Iranian regime, and then in response agreed to ratchet down the sanctions, then they could achieve their stated goal of a non-nuclear Iran without violence.
So if the UN is essentially lying about its intentions and using increasing sanctions to force regime change in Tehran, what should the response of the Iranian leadership be? Operating on the premise that the western nations will be much more restrained in initiating open warfare than they would have us believe, Iran has a certain freedom of action that I would expect to see them begin to exploit as the domestic economic hardships become more disruptive. The risk is that they will miscalculate and cross an unrecognized 'red line' that would draw a violent response that will then escalate to full-scale regional war. But it's also possible that, in light of the deep concern over the anticipated widespread effects of a war in the Gulf, there can be a significant exchange of fire, perhaps in the Straits, that does not provoke a full scale attack. That said, I don't think they can actually attack a tanker in the Strait and avoid having it escalate to war, but they can begin to act a lot more provocatively. It is, after all, their coastal waters, and if anybody has a right to utilize them, it would be Iran rather than the US. They could certainly adopt the 'recalcitrant five-year-old' approach and simply do everything we don't want them to do until sanctions are relaxed. They could increase enrichment, missile R&D, support for Hezbollah and Syria, make peace with the Iranian Kurds, become more active in Iraq - all with the understanding that these initiatives will end when sanctions are lifted.
On the current trajectory, I don't think you can expect to see war with Iran this year at least, and I don't expect to see concessions from Iran if they don't result in reduced economic sanctions. What I do expect to see, however, is some increasingly belligerent and aggressive actions from Iran as they search for ways to make the west reconsider their program of non-negotiable sanctions.