Why didn't the United Nations send troops to destroy the Islamic State?

Reprint and know the author. Don't you know that my fundamental reason is that the cost of fighting isis outweighs the benefits?

Why the Middle East was chaotic before is very simple, because a chaotic Middle East is in the best interests of all parties. In a place where strategic resources are so concentrated, if there is a powerful unified force to control energy, no one among the five hooligans wants to see it. So we have to do everything we can to make him screw up, and then everyone will get his place?

So, you see isis is now bombing cultural relics, killing children and burning them at the stake. I feel heartbroken and I hope someone can stop it immediately. However, if we really want to rise to the consideration of international politics, these are not important. Is reality so cruel?

But now the situation is out of control, and everyone is not sure what to do next and what accidents will happen. Fortunately, we are not mired in chaos in the Middle East, so we can protect ourselves and wait for the situation to develop.