They probably struggle with the numbers, its almost like a bandwagon, think about it, it might start with a young guy going to his friends saying "hey guys, they've insulted our prophet, we have nothing better to do so lets go trash the embassy", -insert snowball effect- and you have an almost uncontrollable number of aggressive, uncivilised people. Within any society, you get some who are peaceful followers, and then you get the percentage that is a little bit corrupt and aren't really occupied with anything, be it a job or education. You could kind of make up many reasons as to why such a huge number becomes hard to control, nevermind suppress.