The Houthis, as the rebels are known after the name of a leading clan in the remote and spectacularly rugged region, have survived the repeated assaults not just of Yemen's own modern army but also, in the latest campaign, heavy bombardment by the Saudi air force's Tornadoes and F-15 fighter aircraft.
Aside from the night of March 21st, the bombardment of Baghdad and of other cities such as Kirkuk, Mosul and Tikrit by aircraft and cruise missiles has been less destructive than was widely expected.