A four-way summit on Syria has ended with no major breakthrough, even as the leaders of Turkey, Russia, Germany and France agreed that a fragile ceasefire in Idlib should be preserved and said a committee tasked with drafting the war-torn country’s new constitution needs to convene by the end of the year.

Saturday’s meeting in Istanbul was aimed at laying the groundwork for an eventual peace plan in a country devastated by more than seven years of war.

In a joint communique following their meeting, Turkish President Recep Tayyip Erdogan, German Chancellor Angela Merkel, French President Emmanuel Macron and Russian President Vladimir Putin called for “an inclusive, Syrian-led and Syrian-owned political process” and said conditions needed to be created for the safe and voluntary return of refugees.

The summit, which was not attended by any Syrian groups, was the first to bring the four leaders together.

Erdogan said the constitutional committee, which was first agreed upon in January during Russian-sponsored talks at the Black Sea resort of Sochi needed to convene “as soon as possible”.

However, efforts to bring Syria’s warring factions together to draft a new constitution under which elections would be held have stalled, with the committee failing to meet even once.

Syria’s major opposition groups had boycotted the Sochi event, officially known as Syrian Congress of National Dialogue, and rejected the constitutional plan. The fate of President Bashar al-Assad, a major sticking point that has repeatedly caused negotiations to fail, had not been mentioned in the final statement of the Sochi summit.

“The people of Syria will determine the future of President Bashar al-Assad,” said Erdogan, whose administration backs certain rebel groups in Idlib.

“As far as we are concerned, Assad is someone who has killed nearly one million of his citizens. He is not someone who we hold in high esteem. Massacres continue as before, but it is our wish that this process comes to an end and the people of Syria can begin to live their lives again.”

Since the beginning of the Syrian uprising, hundreds of thousands of Syrians have been killed and over 12 million people – half the country’s prewar population – have been displaced.

Erdogan said while Turkey had welcomed more than three million Syrian refugees, “they should be allowed to return to Syria, and this should be done in a voluntary fashion.

“With the cooperation of the United Nations, this can and should be done,” he said.

Putin: Demilitarised zone is temporary measure

Also discussed at the summit was a demilitarised zone around the densely-populated Idlib province, a Turkish- and Russian- backed initiative aimed at preventing a large-scale military assault on the last rebel enclave in Syria.

Europe wants to avert new refugee wave Al Jazeera’s Zeina Khodr, reporting from Istanbul, said France and Germany were attending the summit because they want the situation in Idlib to “remain quiet” and “do not want an offensive that will create a humanitarian catastrophe and a new wave of refugees reaching Europe”. “France and Germany are in attendance on the basis that there will not be a Syrian government offensive on Idlib,” said Khodr. “Meanwhile, Russia and Turkey want Europe on board to help pay for Syria’s reconstruction. “They do not believe the West should wait for a political solution agreed by all those involved in the crisis before reconstruction work begins. “But Europe and the US don’t see it that way. “What is also significant about this summit is that France is trying to mediate between the Russian and the Americans – what we’re hearing is that Macron is trying to set-up a high-level meeting in Paris. At the end of the day, you’re going to need the US on board if you want to reach an internationally backed-deal to end the war.”

Putin, a major backer of Assad, called the 15-20km zone “a temporary measure”, adding that he hoped “the Turkish government will ensure, in the near future, the complete withdrawal of the [armed] opposition from the zone and heavy artillery”.

On Friday, Syria’s UN envoy Bashar al-Jaafari also called that the buffer zone “temporary”, adding that Idlib would eventually revert to government control.

An estimated three million Syrians live in Idlib, half of them already displaced from cities and towns under state control.

Putin added that Moscow reserved the right to help Damascus “eliminate terrorists” in Idlib in the event of any provocations.

According to an agreement brokered between Ankara and Moscow last month, opposition groups are to remain in areas where they are already present in Idlib, while Russian and Turkish forces will carry out joint patrols in the area with a view to preventing a resumption of fighting.

For her part, Merkel renewed a call for elections and said “all Syrians must be allowed to decide the country’s future, in free, transparent elections which must be supervised internationally”.

Meanwhile, Macron called on Russia to exercise “very clear pressure” on Damascus “which depends on it for survival”.

A final statement from the four leaders also rejected “separatist agendas aimed at undermining the sovereignty and territorial integrity of Syria as well as the national security of neighbouring countries”.

Al Jazeera’s Zeina Khodr, reporting from Istanbul, said “there was little consensus” among the Istanbul summit attendees, adding that “the differences of opinion were out in the open”.

“France attended the Istanbul summit because they wanted to get a guarantee and a commitment from Turkey and Russia that the Idlib deal to create a demilitarised zone will become a lasting ceasefire.

“But we know that Russia and Turkey wanted a commitment from Europe to help pay with the reconstruction of Syria – and Russia and Turkey did not get that from the Europeans.”

“So, the different players are still so far apart and yet we heard all of them say there is a need to get other players on board.”

‘V ote of no-confidence to US’

Joshua Landis, director of the Center for Middle East studies at the University of Oklahoma, described the Istanbul summit as “a big departure” from the United Nations-backed Geneva process and “a vote of no-confidence to the US”.

Speaking to Al Jazeera, he said “the big gain” for Erdogan is getting “Europe involved into the Astana process”, referring to a separate diplomatic track led by Turkey, Russia and Iran in Kazakhstan’s capital.

“Erdogan wants to counterbalance Russia with some German and French muscle to stabilise the Idlib situation and make sure that Russia and Syria don’t invade and drive all these rebels and jihadists into Turkey, as well many more Syrian refugees which would be a disaster for Turkey and very bad for Europe.”

Commenting on the talk about constitutional reform and “free and fair elections”, Landis said “that is not going to happen”.

“Assad won this war and of course this is a fig leave being brought by Europe – and of course the US behind it – and Turkey, saying that somehow we are going to get the opposition in power in Damascus,” Landis said.

“Assad fought this war brutally in order to stop that and Russia sided with him. I don’t think that these peace negotiations are going to end up winning the war that the militaries could not do in the country.

“But there are many issues, including what is going to happen to all those rebel fighters in Idlib? Are they going to be destroyed and arrested or are they going to own a country, a little enclave, protected by Turkey and Europe?”