"Despite objections from the United States, Moscow could be inching closer to a deal with Tehran whereby the Islamic Republic of Iran could obtain the advanced S-400 Triumf missile air defense system [which was developed and produced by Almaz-Antey]. [Russian] Ambassador Levan Jagarian told the Resalet daily newspaper that Russia saw no problem in moving forward with a sale of the platform when the United Nations arms embargo on the Islamic Republic expires on October 18.
'We are not afraid of the U.S. threats and we will live up to our commitments,' said Jaragain, and that reportedly included considering Iranian arms requests despite pressure from the United States and its allies to isolate the government in Tehran." (National Interest, "Is Russia’s S-400 Air Defense System Heading to Iran?" 1/13/21).
In December 2016, Russia’s defense manufacturer Almaz-Antey and Iran’s Shiraz Electronics Industries signed an agreement on cooperation.
Reuters: "Russian state arms producer Almaz-Antey said on Tuesday it would supply Iran with the advanced S-300 missile system once a commercial agreement is reached. The company's chief executive, Yan Novikov, confirmed Moscow had removed restrictions on deliveries to Tehran that were imposed under pressure from the West in 2010. He did not say when the deliveries might go ahead or how close a deal was. 'All restrictions have been lifted by the political authorities. When there is a contract, we will supply the system, including to Iran,' he told a news conference when asked whether Almaz-Antey would supply the missile system to Iran. President Vladimir Putin signed a decree in April ending the self-imposed ban on selling the S-300 system to Iran." (Reuters, "Russian firm to supply Iran S-300 missile system once deal agreed," 6/2/2015)