The assumption is that war and terrorism is unwanted by the ruling powers.
Remember that money talks. War, terrorism, in particular destruction, generates money.
It's not tinfoilism, it is what causes war to never quite end. Watch for yourself, it's not gonna end. It has gone Orwellian, and has done so long ago. America has become an expert in constant warfare, why? Because America is one of the most money-ruled nations on earth.
Russia is following closely, and has been paying money for continous warfare since they stopped being commie - almost on the day, continous
While America bombed Serbia, Russia bombed Grozny, they then shelled half of Dagestan, then more of Chechnya, Ingushetia and Dagestan. They fuel insurrection in - then get involved in Ossetia and Abkhazia, and in the process go to outright war with Georgia, and invades them - a scenario almost every neighbor of Russia expects at some point.
They're finally done with Georgia, go back to simmering instabilities in the Caucasus, before they invade Ukraine - this time "unofficially", since the invading forces are Russian civilians, technically speaking.
ISIS is quite similar to the Ruski volunteers, a bunch of disgruntled UK-Moroccan rappers and whatnot. They have lived 20, 30 years in a liberty where decapitation seems completely surreal. We have seen the simplicity of terrorism as of late, take a rifle, start shooting people. We have seen the very simplicity of government in action, coups, the hands-on-potential of it, so - fully inspired, ISIS are encouraged to just go hands-on on the middle east, decapitate anyone refusing to leave parliament, and simply taking their own seats in the building "We have a caliphate now!" Yes. Yes you actually do, that is how simple it is to create a country. The panicking plebs are now your population to do as you wish with. Except, of course, it is equally simple to depose them, and replace them. Change of government is simple both days.
ISIS are encouraged not by themselves, but by "higher powers". I've seen unconfirmed suggestions that ISIS have backgrounds primarily in Mossad, but also in UK, French and American intelligence, and I am not surprised AT ALL. Again, no tinfoil: It isn't difficult, impossible or unlikely to create armed terror-groups discretely. People imagine it is VERY complicated, but IT IS NOT. It is VERY - VERY easy. People are so hard-coded to freak out by themselves, you only have to give them an umbrella to organize under, and physical arms and ammunition, and some actual - practical guidelines.