Strasbourg shooting: Why known extremists can carry out terror attacks

The gunman who killed three people in Strasbourg’s Christmas Market had been radicalised in prison, French authorities say.

Sadly, the reality that they were aware of Cherif Chekatt, but unable to prevent the attack, follows a pattern seen in other countries.

At George Washington University, we have looked at 76 jihadist attacks in Western Europe and North America in recent years. We found that more than half involved perpetrators who had been on a security service watch list.

In France alone, the examples are plentiful.