And somehow Russia comes out of this mostly better off once again. 
They get to strengthen their regional influence by way of Iran, while still keeping nuclear weapons out of the fray, which they certainly will use all of this as cover to uphold current relations, and it drives yet another wedge into the post WWII western alliance through these secondary sanctions that could do real damage to long-term relations. An alliance that Putin has sought to weaken for years now. Oh, and the sanctions the Trump administration is seeking to reimplement would predominately harm Iran's oil sector, giving Russia greater leverage and better deals, as many will no doubt choose access to American markets over access to Iranian oil.
I don't see how this benefits Russia at all.
Iran is an ally of Russia they will feel the sanctions and Putin's coffers are empty after he bungled Ukraine and had to step into Syria. He gained nothing from both adventures financially.
Also, the Israeli and US air force is freely engaged in Syria and the world can see that the Russian anti-air weapons do jack shit.
As always the Iran thing has an economic background. The EU, looking to prop up the economy went balls deep into Iranian business after the sanctions were lifted by Obama.
They sold airplanes and whatnot to the regime and got all sorts of oil/gas contracts in return. US businesses were either snubbed or very cautious of entering the Iranian market. The only reason the EU is scrambling to save the deal is because they now have significant stakes in Iran. They were actually warned to not go all in because the deal (even under Obama) was flimsy in the first place but they did so anyway.
Trump and the Republicans have been gunning for this deal for ages. The EU should've tried to stall and keep Trump tied to it by a promise renegotiation or a second look or whatever. The moment the Iranians shut the door on making a 'better deal' with Trump they fucked themselves. And let's be honest here. The EU might like their newfound Iranian business but they won't risk a global economic crisis to keep it going and Trump has friends in Poland, Hungary and other states. There's never going to be unanimous retaliation coming from the EU only some weak-ass statement that they disagree with Trump and try to keep the deal alive themselves (to save their business deals).
Bolton might be crazy but he ain't stupid. He's a smart fucker, he knows all about how the global economic and power structure works. Which is why his first statement was: "I'm giving the Europeans months to pull-out from Iran starting from now"
