Rational? Seriously? Rouhani’s been just as radical as Ahmadinejad, and perhaps more fervent than Ahmadinejad over Iran’s acquisition of nuclear weapons, and they’re more “rational”. The apples/oranges comparison of Vietnam/Cambodia is not helpful, with all due respect.
The only point is ISIS is winning the hearts of minds of those who want to bring about a Caliphate, and that is supposed to be Iran’s domain.
Iran is more rational in the sense that they are not beheading Christian children.