They've killed a lot more than 129 people (along with many other atrocities). There have been thousands dead already but I guess they don't count since they weren't in a first world country.
More like it is a bit more difficult to arrest someone who is part of an armed organization in a different country.
Why would they be using social media to communicate with each other when they're bivouacked together?
Not that the West really has the stomach to stop ISIS.
It's not that they do not have the stomach for it.
They see advantages in having a scary enemy to distract from other issues.
All we want to do is send planes over there to drop bombs and let the smaller countries from the area do the fighting on the ground.
Because once a bomb is used, a replacement has to be purchased. Which means a LOT of money flowing from taxes to vendors.
Getting rid of them is going to take putting troops over there but the people here don't want to deal with the casualties that would come with that.
That is what created them the last time.
At this point there is no clean/easy way to deal with the mess we created. And we aren't willing to spend the money/years helping them if our vendors do not see a cash ROI.