The news that the third London Bridge terrorist was an Italian national suggests that the European ideal of the free movement of people is now over. For the United Kingdom, it was going to end anyway when we left the European Union, but the effort to counter terrorism means that it is likely to be over across the continent within a matter of years.
Of course, this does not follow in a direct line. Most of those responsible for terrorist murders in this country are home-grown, just as they are in France and Belgium. And we must never allow terrorist outrages to feed xenophobia or anti-immigrant sentiment. One of the heroes of the London Bridge attack was Florin Morariu, the Romanian baker who hit one of the murderers with a crate. In London and Manchester, the attacks have united people who have been “born here and drawn here”, as Tony Walsh, the Mancunian poet, put it.
However, the story of Youssef Zaghba that is emerging, of a young man born in Morocco with Italian citizenship who had lived in Ireland, would probably have led to greater restrictions on movement in and out of the UK even if the country had not voted to leave the EU. The Italian intelligence services claim to have tipped off the British authorities about Zaghba after he was stopped at Bologna airport and prevented from travelling to Istanbul last year.
The same pressure to keep closer tabs on terrorist suspects is being felt across Europe. The Schengen Agreement, the EU no-passport zone, has been repeatedly suspended between various countries in recent years.
The Independent regrets the curtailing of the European dream, the freedom of which Caroline Lucas, the co-leader of the Green Party, in particular speaks so movingly, to live, love and travel across the continent. But all European states recognise that their first responsibility is to protect their citizens.
Many of the leaders of the EU, Angela Merkel prime among them, speak resolutely of the four freedoms of the Union: of goods, capital, services and people, and of their indivisibility. But there is a fifth freedom that cannot be ignored, and that is the freedom from the fear of murder. Free movement is already constrained in practice, not least by a system of surveillance and watch lists, so what will happen in the coming years is a matter of degree rather than of principle. It is a shame that movement will become more constrained rather than less, but the peoples of Europe will demand it.
The post-war European dream will have to adjust to new threats. Despite some of the more colourful warnings from David Cameron in the EU referendum campaign last year, the modern security threat in Europe is no longer that of war between nations, but of terrorism.
The great paradox of Brexit is that it is part of a movement that is happening across Europe. In many ways, the British referendum concerned the wrong question at the wrong time. If Mr Cameron had been more resilient in fending off his internal opposition in the Conservative Party, it could be that restrictions on freedom of movement over the next few years might have made the referendum unnecessary.
As it is, it looks as if we will have to observe the end of the one of the founding principles of the EU from the outside.
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