Tunisia is an obvious target - but a particularly depressing one

So militant islamism has spread another chilling tentacle; this time to reach Tunisia.

This afternoon's bloody events at the Bardo Museum follow a dismally familiar scenario.

The target was an obvious one - westerners and a tourism industry on which the country's economy so relies.

But there's something particularly depressing in all this.

Tunisia is where the Arab Spring began back in January 2011. A dictator overthrown in an unlikely outpouring of hope and people power.

The transition to democracy has been long and hard and had many ups and downs.

Yet late last year, an elected President took office as the head of a secular state.

But this has barely masked a muscular and growing force of Islamist radicalism.

Young Tunisian fighters are among the largest component of the foreign legions joining ISIS.

Events are still unfolding in Tunis, but it seems they've now turned their guns on their own country.