Semper Fidelis, Semper Liber.
Stolen fair and square from the Capt. Courtesey himself.I spit at lots of people through my computer screen. Not only does it "teach them a lesson" but it keeps the screen clean and shiny.
Sure, right now there's no way they can make good on those threats. However, given time and a less than enthusiastic bent to go at them head to head on the ground, they will only get stronger.
To conquer them will take ground forces, and a long, LONG, time given that they can recruit from around the world for replacement jihadists.
Everything in your life is a reflection of a choice you have made. If you want a different result, don't blame someone else, or expect others to make a change, you should stop complaining and make a different choice. Remember, the circumstances of your birth don't determine the outcome of your life.
Putin has supported the Ba'athists / Assad regime for many years now; Syria hosts (afaik) the only Russian base on the Mediterranean.
It's not much of a surprise that IS would toss some rhetoric in Russia's direction. The real question is whether Russia will actually do anything about it, other than send more weapons to Assad's forces, and continue to thwart UN action against the Assad regime.