Russian President Vladimir Putin's spokesman Dmitry Peskov says the diplomat's assassination is tantamount to an attack on the country.
The spokesman says the murder is a provocation to Russia, and aims to sabotage the peace process in Syria. He says Putin sees the killing as a terrorist attack and a blow to Turkey's prestige.
The Kremlin website says Putin posthumously gave the ambassador the Hero of Russia award -- the country's highest military honor. Karlov was giving a speech at an Ankara art gallery on Monday when he was shot and killed by an assassin.