Sanctions are not designed to change the regime. Look at the French president complaining how it’s “not fair” the the US seize the moment to lure European manufacturers to the USA.

The Iranian nuclear deal, until some stable genius ripped it appart.

It definitely put pressure on Rhodesia and South Africa, both of which eventually experienced regime change.

No idea about Rhodesia but for SA I think it was mainly doing of ANC

I would agree for Rhodesia. They became much like an island with the outsiders making sure that the authoritarian Mugabe had the stage to enter so he could flush the whites from the farm so foodstuffs would evaporate and hyperinflation set in.

I almost wonder if racists in SA and Anglo nations set the stage for sanctions so Mugabe could rise so the blacks could starve. They knew the food supply was safer under direction of Rhodesian regime.

Cast your mind back to WW2, where the Allies' sanction of Japan basically set the wheels in motion for their collapse.