Turkey has sold military defense supplies to Ukraine. This should not be surprising. Turkey has been increasing its military cooperation with Ukraine for years. Looking at a map one can see why.
This speaks to the true state of Turkish-Russian relations. There has been speculation that Turkey is growing closer to Moscow. Many point to such things as Turkey seeking to purchase the Russian S-400 missile system as evidence for this. However, the idea that these things are merely an act of convenience is rarely considered. Regarding missiles, Turkey is merely looking for an alternative to the US patriot system. Russia happens to provide one of these alternatives.
Turkey is growing stronger, and with that comes an increasingly independent line of action. Part of this involves Turkey reducing its dependence on one of its long time allies --- the United States. While Turkey is not yet ready to abandon its military relationship with the US, it does want to gain leverage over it. That irritates the US. By making friendly gestures to Russia, Turkey can play the two countries off each other.
We must not forget that, traditionally, Turkey and Russia are enemies. Just over three years ago, Turkey shot down a Russian jet from Syria. Russo-Turkish competition has resulted in more than a few wars through the centuries. They include the Sea of Azov campaign of 1695-96, the Pruth River campaign of 1710-11, the Russo-Turkish War of 1735-39, the Russo-Turkish War of 1768-74, the Russo-Turkish War of 1787-92, the Russo-Turkish War of 1806-12, the Russo-Turkish War of 1828-29, the Crimean War of 1853-56, the Russo-Turkish War of 1877-78, World War I, and the Cold War.
The regional interests of both countries largely oppose each other. There are three main areas where Turkey and Russia clash: the Caucasus, the Middle East and the Black Sea Basin. In the Caucasus, both Turkey and Russia seek to create buffer zones to protect their core territories. For Russia, that means securing the North Caucasus. If an invading force were to cross over from the Caucasus Mountains, they would have an easy, open march towards Moscow. For Turkey, that means protecting the eastern flank of the Anatolian Peninsula from not only Russia, but also Persia.
In the Middle East, Turkey and Russia support opposing sides of the Syrian Civil War. Turkey supports the Syrian rebels, Russia the Syrian government. Their attempts to cooperate in demilitarized zones such as in Idlib is more to reduce the risk of direct conflict than to build a military alliance.
In the Black Sea Basin, Russia wants to secure its access to the Mediterranean, and by extension, the open ocean. Most of Russia’s coastline is frozen for parts of the year, so the Black Sea is its only viable warm-water access. The problem is that the exit from this sea, the Bosporus Strait, is a potential chokepoint that is controlled by Turkey. For its part, Turkey is concerned about Russian activity in the Black Sea and in the lands that surround it, which infringes close to its territory. There’s a reason why Turkey didn’t accept Russia’s annexation of Crimea.
When looking at the future of Turkish-Russian relations, two important things must be taken into account: the history of the relationship, and the interests each country possesses. Add the consideration that Turkey is a rising power and Russia a declining one, and one can map out the general direction of where the relationship is headed.