Sergey Ivanovich Kislyak is a Russian senior diplomat and politician. Since September 2017, he has represented Mordovia in the Federation Council, the upper chamber of the Russian legislature. Previously he served as the Ambassador of Russia to the United States from 2008 to 2017. From 2003 to 2008, he was the Deputy Minister of Foreign Affairs, and from 1998 to 2003, he served as the Ambassador of Russia to Belgium and Russia's Head of Mission to NATO.