On Monday, a Turkish policeman shot dead Russia's ambassador to Turkey Andrei Karlov. Both Moscow and Ankara condemned Karlov's assassination, saying the act was an attempt to thwart efforts to repair bilateral ties, which had been strained because of the two countries' support for opposing sides in the Syrian civil war.

Despite being condemned by the United States and the United Nations, the assassination partly reflects the tense relations between Russia and the West. That Turkey being a NATO member and part of the United States-led campaign against the Islamic State group have further complicated the Russia-West ties.

This year has been bumpy for Russia-West relations. In his televised state-of-the-nation address earlier this month, Russian President Vladimir Putin said Moscow hopes to normalize ties with Washington and is ready to jointly tackle global challenges such as terrorism if its interests are respected. But relations between Russia and the West have remained tense since the Crimea crisis in 2014.