Germany has in recent years been acting more forcefully against extremism, and banned several extremist groups — including several far-right and Muslim organizations. The latest crackdown comes after a spate of attacks by Muslim extremists and far-right groups plotting to overturn the country’s order.

A survey in the United Kingdom has found evidence that Muslim preachers in British mosques lack the language and professional skills needed to tackle radical views among the young. A BBC study has found that only 8 per cent of Imams were born in Britain ...