داخل مدينة الخطوط الأمامية في اليمن بينما يتقاتل الحوثيون من أجل السيطرة

"This is the first drone," said the soldier accompanying us in south-western Yemen. "It's usually followed by an attack."

The buzzing sound overhead got louder as we took cover under the bushes, before climbing back into the vehicle and driving away.

Within about 10 minutes, the loud thuds of strikes followed, one after another, though it was unclear where they landed.

It is hard to tell where the front line begins in the mountains south-west of the city of Taiz.

Saudi-backed pro-government forces are battling to push back Houthi fighters, who swept down the coast of the Red Sea earlier this month, taking control of a key shipping chokepoint and escalating Yemen's civil war.

We travelled with government forces from Taiz through checkpoints to the line where their control ends and no man's land begins, in order to see the fighting up close.