ISIS is also keen to target Italy now because it’s one of the few major European countries it hasn’t yet struck. They’re hoping to inspire violence there so that they can say, in effect, 'we’ve already attacked your capitals in London, in Paris, and in Barcelona, and now we’ve attacked Rome. There’s nowhere we can’t reach.'
The challenge for do-it-yourself terrorism is pretty significant. They download the app, they might click on a hashtag and then they're one or two more taps away from connecting to someone who could point them in a violent direction.
Defeating the Islamic State will be the easy part. The hard part will be securing the peace, making sure that the forces converging on Deir Ezzor don't start fighting among themselves. The stakes for Deir Ezzor could not be higher. The Iranians want an overland route to the Mediterranean. The Kurds want a buffer between Assad's forces and their territory further to the north. In some ways, the situation is like the end of World War II, when Soviet and American forces converged on Berlin.
The US has flaked out on the Kurds in the past, so it's understandable that they're worried about US withdrawal in Syria now, but in this case, the US won't be going anywhere for a while. Once ISIL is defeated, the US will need proxy forces on the ground to push back against both Assad and Russia.