Details on the EU dinner are sparse. But there is increasing concern over the role social media plays in disseminating extremist propaganda, as well as being used as a direct recruitment tool. However, there is also a significant worry that placing strict controls on social networks could actually hinder counter-terrorism efforts. "The further underground they go, the harder it is to gleam information and intelligence," said Jim Gamble, a security consultant, and former head of the Child Exploitation and Online Protection Centre (Ceop). "Often it is the low level intelligence that you collect that you can then aggregate which gives you an analysis of what's happening." Mr Gamble was formerly head of counter-terrorism in Northern Ireland. There were, he said, parallels to be drawn. "There's always a risk of becoming too radical and too fundamentalist in your approach when you're trying to suppress the views of others that you disagree with. "In Northern Ireland, huge mistakes were made when the government tried to starve a political party of the oxygen of publicity. I would say that that radically backfired."

Alyattes, who waged war against Deioces' descendant Cyaxares and the Medes