OK, so what? Obviously we shouldn't continue trading with enemies regardless of the economic impact.

Why? If the objective is to weaken a regime, and the sanctions strengthen it, why should you help your “enemy”?

The classic mistake here is to consider that dictatorships are like democracies—they aren't, and their power structure is different and more resilient to economic shocks. Even Bachar Al-Assad, who was much weaker, took 13 years to leave power.

At some point, one should question if wide sanctions targeted at increasing the suffering of the civilian population are really worth it.