Russia says the de-escalation zones agreed to be formed in four conflict zones across Syria will be closed for warplanes of the US and its coalition allies.

“In terms of their actions in the de-escalation zones then from this moment these zones are closed for their flights,” the Kremlin’s envoy to peace talks in Kazakhstan Alexander Lavrentyev was quoted as saying by Interfax news agency. 

The Russian diplomat added, “Aviation operations, especially by the international coalition forces, are absolutely not envisioned.”

He was speaking a day after the fourth round of negotiations between the Damascus government and armed opposition came to an end in the Kazakh capital, Astana.

During the talks, Iran, Russia and Turkey, as mediators and guarantors of the ceasefire regime in Syria, brokered a memorandum on the creation of four de-escalation zones in areas where the most intense fighting is taking place between Syrian government troops and different militant groups.

Iran and Russia are allies of the Syrian government, while Turkey backs different militant factions. The trio is tasked with observing the implementation of the ceasefire regime, which was agreed last December and helped launch the Astana peace process a month later.

The memorandum was adopted based on a Russian proposal to single out four hot spots in violence-hit areas of Syria, including the provinces of Idlib and Homs as well as the eastern Ghouta region near Damascus.

Under the plan, Damascus and the militant groups, which are party to the Syria-wide truce, will stop all clashes and the use of any kinds of weapons in the security zones. The measure is meant to facilitate the progress of the diplomatic process as well as aid deliveries to civilians in the troubled areas.

Lavrentyev said Thursday that that under the plan Russia could send observers to safe zones. He said third-party monitors could be invited provided Iran and Turkey agreed.

Also on Thursday, top Syrian negotiator Bashar al-Ja’afari praised the latest round of Astana talks as an “unprecedented” leap forward in the peace process aimed at finding a political solution to the deadly Syria crisis.

UN Secretary-General Antonio Guterres welcomed the memorandum.

Guterres “welcomes the commitments to ceasing the use of all weapons, particularly aerial assets; to rapid, safe, and unhindered humanitarian access; and to creating conditions for the delivery of medical aid and meeting civilians’ basic needs,” his spokesman said in a statement released by the UN.

The UN chief believes it is “crucial to see this agreement actually improve the lives of Syrians,” the statement added, reaffirming the world body’s support for a peaceful settlement of the Syria crisis.

Earlier in the day, Staffan de Mistura, the UN’s Syria envoy, hailed the deal as “an important, promising, positive step in the right direction in the process of de-escalation of the conflict.”

The Syrian Foreign Ministry also issued a statement in support of the initiative.

The fourth round of Astana talks held on Wednesday and Thursday was also attended by US and Jordanian observers.

This is while the armed opposition delegation, representing over a dozen militant groups, has so far rejected the memorandum, claiming it poses a threat to Syria’s territorial integrity.