The TV news bulletin on Euronews of November 20 showed a security exercise being held in Antwerp, Belgium.
Just in case. Hopefully never.
The commentator said, in the meantime, that it was extremists, who are often some 10 per cent of any group of people, whom we should fear. Not the majority peace-loving 90 per cent of people.
And, while never exaggerating, we need to beware of, and be prepared for, violent activities from extremists.
This often applies insocial, political and even religious groups.