Europol: New Paris-Style Attack Hard To Stop

The head of the EU's police agency Europol said there are no guarantees that another Paris-style terror attack can be prevented despite increased security measures. Rob Wainwright told Sky News that it has become "extremely difficult" to deal with the threat posed by Islamist extremists. It comes as David Cameron vowed to tackle what he called the "poisonous narrative of Islamist extremism that is turning too many young minds". He was speaking following two days of talks