The West has shown it is totally ineffective utilizing diplomacy and threats. The West has time and again drawn the proverbial line in the sand. Iran has glaringly and arrogantly stepped over each and every single line.
Just as Pletka states in her essay, Western diplomacy is weak and feckless. She uses the example of Joe Stalin, which is true in a Post WWII sense. I think on the other hand it is closer to Adolf Hitler re-arming Germany with a messianic-political mindset of dominating the globe with Arian Nazism.
Iran's goal is world domination via a messianic-political mindset of Mohammedanism. Global politicians pooh-pooh the stated goal of Iran because no-one believes the Islamofascist nation has the resources.
The thing global politicians and diplomats do not understand is the Mohammedan fatalistic mind-set: They don't care if they have the resources to initiate a global cataclysm. For the radical the cataclysm brings the Mahdi (Shi'ite Iranian version). The Mahdi will divinely seal the deal for Mohammedans.
There is no amount of diplomacy or negotiation that will overcome that Iranian mind-set.