On 16 August the Syrian Democratic Forces (SDF) under the leadership of the PKK-affiliated YPG attacked the Assad-regime-held town of al-Hasakah in Northeastern Syria. The town had been an isolated outpost as the area around it was first taken by anti-Assad rebels, then by ISIS, and then finally by the SDF. The SDF and regimes forces had only fought sporadically before. The only other instance was the takeover of the city of Qamishli earlier this year, but the geopolitical situation was different then. By attacking Hasakah now, however, they made a terrible mistake.
Since before the coup attempt in Turkey on 15 July, Recep Tayyip Erdogan had been trying to warm relations with Russia. After the coup, things went full swing, and the Turkish president signed several economic agreements with Vladimir Putin and there were talks of basing rights for the Russian Air Force in Incirlik AFB. Consequently, Erdogan also began to reach out to the Assad regime, essentially to the “zero problems with neighbors” strategy of the country before 2011. It just so happened to be that Assad and Erdogan had at least one common interest: to quell Kurdish aspirations for independence.
When the SDF attacked Hasakah, it seems that they and their backers had completely ignored the geopolitical ramifications of such a move. By kindling hostilities with the regime, they only created an opportunity which fell right into Erdogan’s lap: they created the diplomatic space to allow for a Turkish intervention into Syria.
One thing needs to be cleared up: the Assad regime is not an independent force. Assad is a puppet of Russia and Iran and any action taken by the embattled leader must be approved by Putin and Khameini.
With Turkish and Russian relations warming, Putin was already considering allowing a Turkish intervention to fray the NATO alliance. He also wants to prevent the empowerment of the Kurds, as this would only eventually weaken Assad. It just so happens to be that you can have both at the same time and Putin did just that.
The Turks and their militias are now fighting the SDF and threatening Manbij, which had been won with the backing of US forces. The Turks and the Americans are headed for a collision course. Russia and Iran are experiencing the best of both worlds. The fact that ISIS is losing areas in northern Syria is only a secondary part of the geopolitical situation in the region.
Read what I wrote about the situation in Hasakah before the Turks intervened.