On Tuesday this week, at least nine Yemeni army troops died when their helicopter was shot down in central Yemen. The country offers the kind of ungoverned space in which the new forms of al Qaeda thrive, operating as groups in their own space, with their own politics, but holding a common devotion to the Bin Laden legacy of global holy war. Such groups are also active in Syria, Iraq, Somalia, the Caucasus, and in the Maghreb, north-west Africa, where the region’s fragility is a major worry for western governments — not least because jihadi extremism from there infects the large Moroccan populations in Belgium and Holland.