Turkey shares a border with Russia. Many of the peoples of the former Soviet Union (aka the Empire of the Russ) were ethnic Turks, spoke a Turkic language, even if they lived in one of the Stans.
Turkey sees itself as the "home" of all the Turkic peoples in the same way Spain sees itself as the "home" of all Spanish-speaking peoples. Furthermore, Turkey. and its predecessor the Ottoman Empire, are historic enemies of Russia, going back centuries.
Know all of the foregoing as prologue to understanding a seemingly innocuous Reuters article which reports a Syrian plane forced to land in Turkey was carrying Russian arms destined for Syrian armed forces. Truly, nothing is "innocuous" in the relationship between Turkey and Russia, or Russia's ally, Syria.
