US-Iran relations reached a nadir following the killing by US drone strike of Quds Force commander Qassem Soleimani. As Iran’s isolation grows, its link to Russia is likely to strengthen. Moscow can use Iran’s geopolitical weakness to its own economic advantage by making large sales of Russian military hardware to the Islamic Republic and encouraging deeper cooperation between the Eurasian Economic Union and Tehran. At the same time, Russia will use the death of Soleimani to constrain Iranian troop activities on the Syrian battlefield and will generally limit Damascus’s dependence on Iran.