Syrian government forces secure a road for a military convoy in the desert area of Saba' Biyar, in southeastern Syria near the border with Iraq, on May 10, 2017, as fierce clashes are reported in the region. (Xinhua/AFP Photo)

DAMASCUS, June 21 (Xinhua) -- Clashes have been gaining momentum in east of Syria's capital Damascus and the the Syrian army was responding with airstrikes and possibly a ground military operation, sources told Xinhua Wednesday.

Damascus has been calm since the internationally-backed de-escalation zones' deal went into effect in May this year.

Both neighborhoods have witnessed the rebel evacuation toward rebel-held areas in Idlib province, leaving the eastern rim of Damascus, known as the Eastern Ghouta, in the hands of several rebel groups, some included in the de-escalation zones' deal while others not.

The al-Qaida-linked group Failaq al-Rahman rained down the capital with mortar shells and explosive bullets, prompting the Syrian army to respond with airstrikes amid information that the army is bracing to unleash a wide-scale offensive on Jobar and Ayn Tarma, a key bastion of the al-Qaida-linked groups.

A military source told Xinhua that the Syrian army is pushing toward Ayn Tarma and Jobar to further secure the surrounding of the capital.

However, the renewed clashes have troubled the capital residents, who have felt a sense of relief over the past few weeks, before the mortars renew again.

On Wednesday, mortar shells struck areas in Damascus' neighborhoods of Mazzeh, Mazra' Baramkeh and also areas in the old city of Damascus, with losses still unknown.