Since August there have been 2 state visits, numerous phonecalls and a number of military visits.
Naturally there is no information, but as Erdogan is distancing himself from the US/EU alliance it seems logical that Putin and Erdogan would be discussing how to share Syria.
Maybe it is not an alliance, but just a letter of intent. In the future Erdogan and Turkey could go back to disagreeing – but the most likely is an alliance. Interesting to see how does it sit with NATO. But President Obama in 8 years has lost a huge channel practically from Iran (or Pakistan that is China leaning) to Syria (and maybe Turkey) to Russia.
Let’s now see how Trump fares.