“Iran has become Russia’s top military backer,” US National Security Council Spokesman John Kirby said.
“Russia’s been using Iranian drones to strike energy infrastructure, depriving millions of Ukrainians of power, heat, critical services. People in Ukraine today are actually dying as a result of Iran’s actions,” he said.
According to John Kirby, Russia is seeking to collaborate with Iran in areas like weapons development, training.
He added that the US fears that Russia intended to “provide Iran with advanced military components” including helicopters and air defence systems.
Co-operation between Russia and Iran has been highlighted recently, with Ukraine accusing Russia of using Iranian drones in its attacks.