Now that Russia has become enemy numero uno again, suspcion has fallen on their attitude toward Iran and the P5+1 negotiations to prevent Iran building nuclear weapons. But why would Russia, right next door to Iran (closer than Israel), want its islamic near-neighbor to have such weapons? Doesn't make sense.
Paul Pillar makes that obvious point. He goes on to speculate that Russia's hint that it might ratchet down its sanctions participation against Iran and begin trading could help bring the negotiations to a successful conclusion.
His argument: "Actually, some opening up of commerce with Iran, whether at the initiative of the Russians or of someone else, would probably help the negotiations....What is most needed now to sustain Iranian cooperation and seriousness is not still more sanctions; if that were true we would have seen results long ago. What is needed more is to persuade Iranians who matter...that all those sanctions really were for the declared purpose of eliciting Iranian agreement to arrangements that preclude an Iranian nuclear weapon. That is needed because the Iranians have been given much reason to be skeptical about whether that is the true purpose of the sanctions. And it is needed because, after the Iranians made major concessions in the preliminary agreement reached last November in return for only meager sanctions relief, they are still waiting for proof that their cooperation is buying the economic relief they seek."
In other words, the Iranians have to be convinced that the sanctions are not finally for the purpose of regime change (the goal of some U.S. policy makers and congress men/women).