[Skybird]

Does nothing. Several Western nations as well as Russia, India and China already undermine existing sanctions. why assuming they will stop that in the future?

The Iranians can easily establish a "counter-blockade": by mining the straits.

The straits are small enough to fully cover them with Iranian ASMs. Do not assume that Silkworms are the best they have. China has had a high interest to let them have better stuff. and both nations have no interest to let anybody know about such deals. that Hezbollah had MILAN and Russian latest generation ATGMs also was completely missed by Israeli and american intel before the Lebanon war.

You can only threaten sanctions when negotiating from a position of strength. The Western position is the position of weakness in this match as long as the option of all-out military strikes is excluded. I do not wish to demand nuclear strikes, but thinking fact-oriented I am sure that a lasting dampening effect on Iran's program cannot be acchieved without nuclear strikes: delay - yes. interruption - no. I am not willing to engage in military action that is half-hearted from the beginning.

There are strategic concerns about Iranian retaliation options that lead beyond Iran, or Hormuz.

You either shut down the program by force, or you accept a nuclear Iran, both civilian and militarily. Iran knows that the EU is willing to accept a nuclear Iran if needed, thus it's diplomacy plays the "winning time"-game. europeans buy it happily. I also do not buy that American determination to go all the way for the prevention of a nuclear Iran, not after the debacle in Iraq and Afghanistan. So, only the Israelis are left, and they have a vital interest and motive to be far more determined than the US and the EU together. If they can handle the challenge or not, I do not comment on, due to lacking knowledge.