Amir Handjani elaborates on why Trump’s Iran policy will fail on its own terms:

The Trump administration has just made the path to a diplomatic settlement with Tehran much harder. It has badly miscalculated the resilience of the regime and its ability to absorb punishment.

Handjani makes several important points that have often been overlooked in the debate over the administration’s Iran policy. First, he notes that “Tehran views its influence in Iraq and Syria as vital to its national security.” If Iran sees retaining its influence in these countries as vitally important for its security, that should tell us that they aren’t going to give up on it because of outside pressure. On the contrary, the fact that a foreign government is telling them to give this up will be much more likely to confirm how important it is to keep it.

The Iranian government’s determination to hold to these policies can be seen from the fact that they have continued them even when they were under much greater economic pressure:

The Islamic Republic has consistently demonstrated that it can do more with less and that it will sacrifice butter for guns.

That conclusion is consistent with this study of how the Iranian government has responded to sanctions in the past. Trying to coerce Iran’s government into abandoning its pursuit of regional influence isn’t going to work because the government places too much importance on it and it is willing to pay a significant price to ensure that it retains the influence it has gained. Sanctions usually don’t succeed in compelling changes in regime behavior, and they are never successful when the regime believes that its security and/or survival would be put at risk by yielding to outside demands.

Iran sanctions can’t achieve the administration’s stated goals, and that is largely because those goals are unrealistic and unreasonable.