Russian President Vladimir Putin has dismissed Aleksandr Grushko from his post as ambassador to NATO and appointed him as deputy foreign minister.
Decrees on Grushko's dismissal and appointment were signed by Putin and posted on an official website on January 22.
No reason was given, and there was no word on a replacement for Grushko as ambassador to NATO.
Relations between NATO and Russia have been badly strained by tension over issues including Moscow's takeover of Crimea, its role in the conflict in eastern Ukraine, and incidents in which the Western military alliance says Russian aircraft have come dangerously close to its planes and ships.
Grushko, 62, began his diplomatic career on 1977 and had been Russia's envoy to NATO since October 2012, five months into Putin's current term.
With reporting by Interfax