When a raiding party from Islamic State of Iraq and the Levant attacked a Saudi border post last week, it was no mere hit on a desert outpost.
The jihadists were launching an assault on the new, highest profile effort by Saudi Arabia to insulate itself from the chaos engulfing its neighbours.
The Saudis are building a 600-mile-long “Great Wall” – a combined fence and ditch – to separates the country from Iraq to the north.
Much of the area on the Iraqi side is now controlled by Isil, which regards the ultimate capture of Saudi Arabia, home to the “Two Holy Mosques” of Mecca and Medina, as a key goal.
The proposal had been discussed since 2006, at the height of the Iraqi civil war, but work began in September last year after Isil’s charge through much of the west and north of the country gave it a substantial land border with the Kingdom to the south.
The border zone now includes five layers of fencing with watch towers, night-vision cameras and radar cameras.