Russian-backed plans for de-escalation zones in Syria are on hold as the US, France and the UK seek further detail on how exactly the agreement will be enforced.

The deal, jointly signed by Russia, Iran and Turkey in Kazakhstan last week, agreed the establishment of four zones intended to halt conflict between government forces and rebels in key areas, and would potentially be policed by foreign troops.

However, the deal has offered little detail on the specifics of the enforcement and in an effort to provide assurances, the Russian foreign minister, Sergei Lavrov, will meet the US secretary of state, Rex Tillerson, on Wednesday in Washington, amid western diplomatic concerns about how the ceasefire will be enforced and monitored.

The Astana agreed ceasefire brokered by Russia, the US and Turkey is broadly holding, but Russia would like the formal political support of the UN Security Council for the agreement, something that requires the backing of permanent Security Council members such as the US.

The Syrian opposition has said it cannot accept a ceasefire agreement being enforced by Iran, as the Astana agreement proposes, while the government of the Syrian president, Bashar al-Assad, has vetoed a role for the UN or other international forces as peacekeepers.



The Syrian government says under the agreement, it will be the duty of opposition forces to help expel jihadi fighters from the de-escalation zones.

However, groups such as the al-Nusra Front have gained military strength in the Idlib region and some moderate opposition forces would be reluctant to join Syrian or Russian forces to make them leave, risking further conflict.



In the US, the debate over the zones is a key test of whether Donald Trump’s administration is able to forge a coherent Syria policy, and a gauge of how much the president is willing to cooperate with Russia to resolve the six-year conflict.

Moscow is investing huge diplomatic energy in the Astana process, reflected in Lavrov’s visit on Wednesday, which makes him the highest-ranking Russian official to visit Washington since the Trump administration took office. But Russia has so far refused to accept western calls for Assad to stand aside as a precondition of a political transition.

On Monday, the US defence secretary, Jim Mattis, highlighted the absence of details in the agreement on enforcement. “It’s not been decided … who’s going to be ensuring they’re safe, who is signing up for it, who is specifically to be kept out of them. All these details are to be worked out and we’re engaged,” he said.

The US state department last week also expressed concern about the involvement of Iran as a guarantor, saying “Iran’s activities in Syria have only contributed to the violence, not stopped it, and Iran’s unquestioning support for the Assad regime has perpetuated the misery of ordinary Syrians”.



It added: “In light of the failures of past agreements, we have reason to be cautious. We expect the regime to stop all attacks on civilians and opposition forces, something they have never done. We expect Russia to ensure regime compliance.”

Trump also faces difficult decisions on whether to inform the Turkish president, Recep Tayyip Erdoğan, that he intends to continue Barack Obama’s policy of providing support in northern Syria to Kurdish People’s Protection Units (YPG) fighters.

Washington and Ankara have clashed over the forces that should be utilised against Islamic State in the military operation to liberate Raqqa, the militant group’s chief stronghold in Syria. Turkey argues that the YPG is the Syrian affiliate of the Kurdistan Workers’ party (PKK), a separatist group operating inside Turkey designated a terrorist organisation by the US.

The Pentagon supports the YPG and has been considering providing arms to it before the assault on Raqqa. Ankara says sophisticated weapons would fall into the hands of the PKK and the YPG’s role in Raqqa’s liberation would be a PR coup for terrorism.

Separately, the UN special envoy for Syria, Staffan de Mistura, has announced that he plans to reconvene the parallel UN-sponsored peace talks on Syria on 16 May.

The discussions in Geneva have stalled on the issue of whether Assad would have to stand aside as part of a political transition, but De Mistura has been using his diplomatic skill to persuade the warring parties to focus on possible points of agreement about a future parliament and transitional body.