A man uses a pickaxe to dig a cave in the Syrian village of Kafr Ain in the southern countryside of the rebel-held Idlib province on September 15, 2018. Residents of Idlib province and surrounding areas have been bracing themselves for a Russian-backed government offensive on the country's largest remaining rebel-held zone. / AFP / OMAR HAJ KADOUR
A man uses a pickaxe to dig a cave in the Syrian village of Kafr Ain in the southern countryside of the rebel-held Idlib province on September 15, 2018. AFP

Fearing attacks from above, Syrians in Idlib head underground