I think Mr. Putin is a very wise & cunning man. See the world oil production map below. If Putin can bring the various militants including ISIS to heel, he will have control over a huge portion of that world oil production. He has backed Iran for years along with Syria. As Obama has frittered-away US influence Russia has worked hard to fill the void.
The top 10 oil producing countries are: US, Saudi, Russia, China, Canada, UAE, Iran, Iraq, Brazil & Mexico. These countries have little or no skin in the middle east now. China is a major purchaser but likely has prior agreements with Russia. The US no longer has leadership worth consideration.
With a solid grasp of middle eastern oil and north African producers, Russia will have all of Europe in the palm of their hand. Between Russia and China they will control energy for all Asia and Japan (unless Australia develops and sells crude to Japs).
That pretty well wraps up the eastern hemisphere folks with deployment of very few troops. Putin is playing in a big game. But, he has a time frame: 18-24 months. US is out of play until after the presidential elections. Even then, allowing the isolationist bent of many voters, there may be no effort (I would bet none) in re-entering the middle eastern quagmire.
In today’s world economic control is by far preferable to military control. A handful of militants can wreak havoc. Kill the krap out of a few terrorists, turn over control to a very heavy-handed dictator and you can name your price.