Russia wants the United Nations Security Council to endorse an agreement reached in the Kazakh capital of Astana last week to establish ''de-escalation zones'' in Syria, but several council members say they need more information before they can back the deal aimed at bolstering a ceasefire.

The memorandum signed by Russia, Turkey and Iran came into effect on the weekend and calls for a truce — renewable after six months — between government and opposition forces in four designated safe zones as well as the delivery of aid and medical supplies. One of the sites includes Idlib province in northern Syria, where dozens were killed following a chemical weapons attack in April.

Russia distributed a draft resolution on Friday asking for Security Council endorsement, but some members feel it's premature.

''The question today is do we have all elements we need to understand the substance of the agreement and the way it is going to be implemented,'' said France's ambassador to the UN, François Delattre. ''The answer to this question is 'not yet'.''

'We hope for more information'

''We want peace and stability and humanitarian access in Syria,'' said Sweden's ambassador to the UN, Olof Skoog. ''We hope for more information before we have to go to a vote on the resolution.''

Council members are expected to meet behind closed doors this week to discuss the terms of the deal. The three guarantors have until June 4 to establish the borders of the safe zones while details on who will oversee the ceasefires and the aid deliveries is not yet clear.

''There will need to be effective monitoring mechanisms as well as full and sustained humanitarian access,'' said a UN diplomat.

Implementing the deal would be ''complicated,'' the diplomat said.

The U.S. expressed skepticism about Iran's role as a ''so-called guarantor'' of the deal, and on Tuesday, in a move that will likely irk ally Turkey, the Pentagon announced the U.S. will provide arms to Kurdish fighters in Syria, a decision the U.S. sees "as necessary to ensure a clear victory" in its planned assault on the ISIS stronghold of Raqqa. 

Lavrov to make case in D.C.

On Wednesday, Russian Foreign Minister Sergey Lavrov will make the case for the Astana memorandum when he meets with his U.S. counterpart, Secretary of State Rex Tillerson, in Washington.

Syria has said it will abide by the deal as long as the rebel forces do so as well but made it clear it does not want the UN involved.


Russian Foreign Minister Sergey Lavrov and U.S. Secretary of State Rex Tillerson arrive for a news conference in Moscow last month. The two are scheduled to meet again Wednesday. (Sergei Karpukhin/Reuters)

"There will be no international forces under the command of the United Nations in the de-escalation zones,'' Syrian Foreign Minister Walid al-Moallem told a news conference in Damascus on Monday. ''There will be no role of the UN or international powers in these areas."

The next round of UN-brokered Syria peace talks is set to take place in Geneva on May 16.

With files from Reuters