Obama has gotten a lot of criticism for failing to support the rebels against Assad, while Putin supported Assad, who had the Syrian military at his disposal. Many of the rebels opposing Assad were affiliated with al-Qaeda or ISIS. The few rebels not affiliated with them were very weak. John McCain’s idea to support the more trustworthy rebels would clearly have benefited Al-Qaeda and ISIS to some extent. Obama pretty much avoided doing that, to his credit. But Obama’s potential allies were weak, while Putin’s allies in the Syrian government were stronger.
People criticize Obama for failing to kill Assad after he crossed Obama’s red line on chemical weapons. I think Obama did the right thing. If Obama had killed Assad, or undertaken a massive invasion of Syria to unseat thim, it’s likely that the war would have become even more violent and even more chemical weapons would have been used. By getting Assad to renounce chemical weapons, Obama significantly reduced their use in the civil war.
In terms of who will win the civil war, Assad’s opponents have never been close to winning, even with foreign support. Assad was not strong enough to win quickly, but he was the only participant who had a chance of winning with only a little outside support. When Russia provided this support, the iide began to turn in Assad’s favor.
It’s not clear whether the end of the war is near, and if so, what it means. Hopefully it will mean less violence and death. It’s possible that Assad will seek revenge against the rebels, continuing the violence and the refugee deluge, but ideally things will be better than they are currently.
Obama could have lessened the destruction in Syria, by supporting Assad despite his unsavory human rights record. Obama could not have led the rebels to victory unless he had sent in US troops for a full scale war. Thus, the easy course of supporting Assad was open to Putin and he took it. He did not expend much in terms of men and equipment, but it appears to have been enough to turn the tide. He comes out looking like a strong man by supporting a human rights pariah.