Syria's army announced Saturday a halt in fighting in parts of Eastern Ghouta after rebels and regime ally Russia agreed on how a safe zone will function for the besieged opposition enclave.
With many of its towns and villages ravaged by bombardments in the six-year conflict, Eastern Ghouta near Damascus is one of the last strongholds of rebels fighting President Bashar al-Assad's regime.
Eastern Ghouta is in one of four proposed "de-escalation zones" designated in an agreement reached by government allies Iran and Russia and rebel backer Turkey in May.
But the deal has yet to be fully implemented over disagreements on who would police the safe zones, and Eastern Ghouta is just the second zone to see a ceasefire enter into force.
The army "announces a halt in fighting in some areas of Eastern Ghouta in Damascus province from midday on Saturday (0900 GMT)," it said in a statement carried by state news agency SANA.
"The army will retaliate in a suitable manner to any violation" of the ceasefire, the statement said, without specifying what areas were included.
Russia said earlier Saturday it had signed a deal with "moderate" Syrian rebels at peace talks in Cairo on how a safe zone would function in Eastern Ghouta.
But no rebel group said it had signed the Cairo agreement, with one influential group in the region saying it was not involved.
The Cairo meeting "follows on from the ceasefire deal for the south of Syria" that took hold on July 9, said Wael Alwan, a spokesman for Faylaq al-Rahman.
That ceasefire for southern areas of Syria was brokered by Russia, the United States and Jordan.
Russia said it and the rebels had signed agreements under which "the borders of the de-escalation zone are defined as well as the deployment locations and powers of the forces monitoring the de-escalation".
It said the sides had also agreed "routes to supply humanitarian aid to the population and for free movement of residents".
Russia said it plans to send in the first humanitarian convoy and evacuate the wounded "in the next few days".
The two other "de-escalation zones" included in the May deal are the rebel-held province of Idlib and northern parts of the central province of Homs.
More than 2.5 million people are believed to live in the four zones.
The May accord roughly laid out the areas where rebels and government forces should halt hostilities, including air strikes, for six months, but Russia, Turkey and Iran then failed to meet a June 4 deadline to set exact boundaries for the zones.
One major stumbling block appeared to be who would ensure security in all four areas, with Turkey and Iran in particular reportedly wrangling to bolster their influence.
A new meeting in the Kazakh capital Astana is expected during the last week of August, with rebels as well as representatives from Turkey and Iran to attend, Russia has said.
Moscow has argued that the zones agreement will provide moderate rebels with security and help focus attacks against Islamist militant groups such as former Al-Qaeda affiliate Fateh al-Sham Front and the Islamic State (IS) militant group.
More than 330,000 people have been killed in Syria since its conflict broke out in March 2011 with anti-government protests.