The complex sat below Ali al-Taher ridge, a strategic hilltop that overlooks the region and that has seen intense fighting.

The Lebanese city of Tyre, one of the oldest metropolises in the world, has been left scarred.

Officials said they had not determined the cause of the explosion. Years of fighting have left Syria littered with weapons and ordnance left over from the civil war.

Amid relentless war in the Middle East, the Iran-backed militants seem poised to renew their conflict with Yemen’s Saudi-backed government.