Russia, Iran and Turkey struck a deal on Friday to jointly police a fourth safe zone in Syria around Idlib province, as part of a Moscow-led plan to ease the country's six-year conflict.
In a joint statement after two days of talks in Kazakhstan, the three countries said they agreed to allocate their forces to patrol the zone covering rebel-held Idlib province and parts of the neighbouring Latakia, Hama and Aleppo regions.
The talks in Astana, the Kazakh capital, are the sixth round of negotiations Moscow has spearheaded since the start of the year as it seeks to pacify Syria after its game-changing intervention on behalf of leader Bashar Al Assad.
Regime backers Russia and Iran and rebel supporter Turkey agreed in May to set four "de-escalation zones" in rebel-held territory around Syria to halt fighting between the government and moderate opposition.
Since then Russia has forged ahead with establishing three of the zones by deploying military police to patrol the boundaries of safe areas in the south of Syria, in Eastern Ghouta near Damascus, and in part of the central Homs province.
However, the three countries had struggled to agree on the details of the final zone around Idlib, on the border with Turkey, as Ankara and Tehran vied to expand their influence.
Idlib was captured in 2015 by an alliance of extremists and rebels and remains beyond the control of the government.
On Friday Russia, Iran and Turkey said their forces would be deployed according to maps agreed earlier this month in Ankara, but gave no further details of their exact positions or the timing.
A joint Russia-Turkish-Iranian coordination centre will be set up "aimed at coordinating the activities of de-escalation forces", their joint declaration said.
Russia's chief negotiator Alexander Lavrentyev hailed the deal as the "final stage" in the creation of the four safe zones, insisting it would "create a real path to the cessation of bloodshed" and offer hope for "a return to peaceful life".
Nevertheless, he acknowledged there remained a "long journey ahead to strengthen trust" between the Assad government and the armed opposition, both of whom sent delegations to the negotiations.
Regime representative Bashar Al Jaafari said Damascus "supports any initiative in Syria that stops the shedding of Syrian blood and decreases suffering".
The armed opposition noted that no "monitoring mechanism" had been agreed for the new zone in Idlib.
"Assad's forces or militias will not be present in any area or part of the de-escalation zones and will not have a role in our liberated zones," a statement on its Facebook page said.
On the ground the "de-escalation zones" have already seen fighting drop and allowed Damascus and Moscow to turn more of their firepower against ISIL.
The participants agreed to a fresh round of talks in Astana next month.
The United Nations envoy for Syria Staffan de Mistura called for bringing "the momentum of Astana" to broader talks on finding a political solution to the war that the UN has hosted without much success in Geneva.
"No de-escalation can be sustained without a comprehensive political process, and that is based in Geneva," he said.
Some observers have viewed the Astana process as a means for Russia, Iran and Turkey to keep the West on the sidelines of any resolution to the Syrian conflict that has already led to the loss of more than 330,000 lives.