Syrian army killed some 10 Daesh militants during the operation, according to the source.
"The garrison of the Deir ez-Zor airfield has repelled an attack by the Daesh militant group. Some 10 militants were killed in the fighting. The Syrian army has hit a Daesh base," the source said.
In late April, Russia's Permanent Representative of Russia to the UN Office and Other International Organizations in Geneva Alexei Borodavkin said that the Syrian army is planning to launch an offensive on Deir Ez-Zor and Raqqa with the support of the Russian air group deployed in Syria.
A US-Russia-brokered ceasefire came into force across Syria on February 27. Syria has been mired in civil war since March 2011, with the army fighting numerous opposition factions and extremist groups. The truce does not apply to terrorist groups such as Daesh and al-Nusra Front.