A scattered collection of rubble, clothes and books is all that remains of the Dar al-Hadith Institute, a Salafist madrassa on the outskirts of Kitaf, a small border town in the north of Yemen.

The Sunni religious school was destroyed so that its conservative followers, including foreign Islamist militants, “couldn’t come back here and start again”, says Abdulkarim, a young Houthi fighter with an AK-47 rifle slung over his shoulder.