All for one
Article Five of the North Atlantic Treaty is very clear: an attack on a member of Nato is an attack on all its members. The article has only been invoked once so far: in the days following September 11. In the aftermath of the Paris attacks some commentators believe it could be activated again but they should be careful. Whatever the rights and wrongs of the invasion of Afghanistan were, there was a certain logic: the attacks had been planned by al-Qaeda, a group that the Taliban continued to shelter. It is not so straightforward now. And what about Turkey? It too is a member of Nato yet there was no call for Article Five following the Isis bombing of a peace demonstration in Ankara last month. A military response may be necessary but Nato members need to tread carefully.