For a decade the west has looked at the Arab world through the prism of a struggle to defend liberal democracy against the march of violent Islamism. The geopolitical landscape is now being remade by the clamour for accountable government in the Middle East. The desire for freedom at home has trumped enmity towards the west.

The Arab spring, as significant a moment as any since the collapse of communism, demands a leap of imagination: a mindset adjusted to see beyond an array of threats to the flowering of a great opportunity. The west has expended vast amounts of blood and treasure fighting wars. What is needed now are resolve and resources to nurture democracy.

The narrative of a generational clash of civilisations looked badly worn long before the killing by the US of Osama bin Laden. Al-Qaeda-inspired terrorism was a serious threat. It remains so even after the death of its prophet. Anyone who cares about security has only to look at, say, Pakistan, Yemen or Somalia.