The Syrian army escalated aerial bombing of a rebel-held valley northwest of Damascus in an offensive that began last week to recapture the strategic area where a major spring provides most of the capital’s water supplies, rebels and residents said on Tuesday.

They said the army shelled and bombarded several towns in Wadi Barada valley about 18 km northwest of the capital in a major offensive launched since Friday. The roads leading to the towns in the valley and the mountain cliffs surrounding the area are under the control of elite Republic Guards and the Lebanese Shia Hezbollah group, they said.

Residents said fighting on Monday focused on Baseimeh village at the edge of the valley where the army and its allies are pushing to advance deeper in an enclave where 10 villages are inhabited by an estimated 100,000 people.

The rebels said the army was emboldened by gaining full control of Aleppo city and was seeking to force the rebels to either leave or face all out war.

“They are seeking to push us into a surrender deal to and we will not hand over our land,” said Abu al-Baraa, a commander in Ahrar al Sham, a rebel group present in the area.

Through a series of so-called settlement agreements and army offensives, the Syrian government, backed by Russian air power and Iran-backed militias, has been steadily suppressing armed opposition around the capital.