I would just add to that, sir. I grew up in South Africa, actually in South Africa under apartheid, and the argument was made that sanctions against South Africa would be disproportionately felt by black South Africans in the townships of Soweto, while white South Africans comfortably ensconced in the northern suburbs of Johannesburg would not feel the impact. Despite this, almost every anti-apartheid leader, including Nelson Mandela himself, has publicly supported sanctions as a tool that helps change the calculus of South Africa's Afrikaner government.
There is no denying that sanctions will disproportionately hurt the average person and will redound, at least in the short term, to the advantage of the Revolutionary Guards and those who are connected to the regime. But ultimately sanctions—economic sanctions, political sanctions, human rights sanctions, terrorism sanctions—undercut the economic power and the political legitimacy of bad regimes. They don't have a perfect track record. They don't work in isolation. They're not a silver bullet. President Rouhani is at the table negotiating with the P5+1 because he was elected by the Iranian people as a result of sanctions inflicting serious economic costs on this regime. Whether that leads to a comprehensive nuclear deal that stops Iran's nuclear bomb, one will wait to see. But sanctions have been a vital instrument of coercive statecraft.