Terrorists are not criminals, they are warriors fighting for a cause that they cannot achieve by peaceful, democratic methods (although they may be considered war criminals if one were to insist that things like the geneva conventions apply to all combatants, and not just government that one happens to disagree with). Like all fighters, they need training-it is not easy to handle explosives and build bombs, much less WMD's. Therefore they need places of refuge, where training camps can be established and run in relative safety. This could be as simple a place as a religious facility (church, temple, or mosque), but it is more effective to have a dedicated facility, like Al Queda was allowed to have in Afghanistan under the Taliban, or Hezbollah is allowed to have in Lebanon. They are not going to be effective in killing your children and your family if you have to guts to confront them on their "safe ground", otherwise the war will indeed be in your hometown.
Austrian police say they expect 10,000 migrants to arrive from Hungary (DPA)
from the article: The victory won't be American