It looks like chaos is breaking out in the Middle East, Near East and Africa. Fundamentalists are keen to take their revenge. Sadly, these standpoints usually stem from earlier grievances and sadly Western Government decisions are often part of these. This is no excuse for acts of terrorism, but long-term grievances often stretch back many hundreds of years.
Think, for example of N.Ireland where today's children are still sectarianised because of events that go back many many generations. The only real answer is if deep trust is rebuilt and this takes generations. War and civil wars and acts of terror are not the answer. In the end, everyone has to be treated with total fairness.