The latest attempt to end the six-year conflict has been organised by Russia and Turkey and begins in the Kazakh capital

Key parties in Syria’s brutal civil war, now stretching towards the end of its sixth year, will meet in the Kazakh capital of Astana this week for a new round of peace talks.

Organised by Russia and Turkey, and backed by Iran, these are the latest in many attempts to shift Syria’s conflict from battlefield to negotiating table.

The conflict has already claimed up to half a million lives and displaced half the pre-war population of 22 million from their homes. But past efforts to end the fighting have come to little, hindered by everything from a lack of trust or any real interest in talks to the absence of powerful Syrian players and their foreign backers.

This latest attempt comes after a huge shift in the balance of power on the ground in Syria that may have created an opening for talks. The meeting has the support of international players whose money and weapons have shaped the progress of the war, and follows a ceasefire that has curbed fighting across much of the country since late December and that has also helped build trust.

But many important parties have not been invited or have declined to come, and there are already tensions about who should be around the table.

One thing all those attending are likely to agree on is that, even if the talks go well, anything that emerges from them will be just the smallest of steps towards ending an extremely complex conflict.

Facebook Twitter Pinterest Syrian and, in the background, Russian soldiers next to a car decorated with images of President Assad, his brother Maher al-Assad and President Putin. Photograph: Pavel Golovkin/AP

Why now?

Late last year Syria’s opposition lost control of east Aleppo, their last major urban stronghold. Syria’s cultural and economic hub before the war, Aleppo had been divided between government and rebel-held areas by a frontline that had barely moved since 2012.

Forces loyal to President Bashar al-Assad finally broke the stalemate with a ruthless siege, months of air bombardment by Russian and Syrian jets that frequently hit civilian targets such as hospitals and markets, then a final ground push by troops including Iranian-backed militias just before the end of the year.

It was a huge boost to Assad, who in 2015 had been within weeks of losing control of Damascus and probably the country. Foreign powers who backed the opposition, and once demanded his removal as a condition for peace, have accepted that is no longer a politically feasible demand.

The election of Donald Trump as US president further diminished prospects for the opposition. His predecessor, Barack Obama, had denounced Assad and offered limited political and military support to the “moderate opposition”. President Trump, by contrast, has said that his focus in Syria will be fighting Islamic State, and has talked about working more closely with Russia to do so.

Facebook Twitter Pinterest US president Donald Trump speaks at CIA headquarters in Langley, Virginia. Photograph: Mandel Ngan/AFP/Getty Images

At the same time, Assad’s own backers, particularly Russia, have grown concerned about the financial and political cost of their bloody campaign. Moscow would like to focus on fighting Isis and, now that Assad’s rule is assured, seems willing to consider compromises on the future shape of Syria.

Turkey, a key supporter of opposition groups, is also apparently willing to try to fumble towards a peace deal. Ankara is in a period of rapprochement with Russia, appears to have accepted that Assad will stay, and is focused instead on limiting the extent to which Syria’s troubles spill on to Turkish soil.

The country now hosts more than 2.8 million Syrian refugees, a growing strain on its own finances. It has become an increasing target for Isis attacks, such as the shooting at a nightclub in Istanbul on New Year’s Eve, that are sowing fear among Turks and undermining the tourism industry.

Ankara is also worried that an intensifying Kurdish uprising is drawing fuel from the military success of Syrian Kurds fighting Isis across the border.

Who will be at the talks?

The talks will brin`g together officials from Assad’s government, some of the Turkey-backed opposition groups fighting him under the banner of the Free Syrian Army, and foreign powers that have played key roles in the conflict.

The talks were, in effect, convened by Russia and Turkey, now that they have a shared interest in ending or at least containing the violence. Assad’s other main backer, Iran, is also supporting the talks and will send a delegation.

On the eve of Trump’s inauguration, Moscow extended a last-minute invitation to American officials to join the meeting, but it is not clear whether they have accepted. Iran has opposed inviting the US, saying the country has played a “destructive” role in the Syrian conflict.

Facebook Twitter Pinterest Bashar al-Assad, left, with Vladimir Putin. Russia is worried by the high cost of backing the Syrian government. Photograph: Alexei Druzhinin/AP

Who’s missing?

Despite the heavyweight delegations from Moscow, Ankara and Damascus, several key parties to the Syrian conflict will not be in Astana.

Perhaps most notable is Isis. The group was never invited or expected, but its absence is a reminder that any deal to bring peace to the majority of Syria would not mean an end to war in a country battered and impoverished by half a decade of conflict.

Isis may be on the back foot after two years of US-led airstrikes and a steady erosion of territory at the hands of a broad coalition of local fighters, but it is not a spent force.

It has battle-hardened fighters, technological skill and a steady income from energy sales to its ostensible enemy, Assad. The recent recapture of the historic city of Palmyra, just a few months after public celebration of its liberation by Russian forces, shows the group is still capable of being formidable on the battlefield.

Also missing will be two of the biggest opposition groups, Islamist hardliners Ahrar al-Sham (AAS) and former al-Qaida affiliate Jabhat Fateh al-Sham (JFS), which controls large areas of opposition-held territory.

JFS was not invited and, after its leadership denounced the Astana talks as “treasonous”, its sometime ally AAS said that it would not take part either. AAS said its decision was partly due to continued Russian and Syrian military activity, but also because it did not want to isolate JFS.

Kurdish forces are also missing from the meeting, apparently at Turkey’s behest, even though they are particularly important in the fight against Isis. Their forces were among the first to halt the military expansion of Isis, in the battle for Kobani at the end of 2014. They have also been a vital part of the alliance pushing towards the militants’ self-proclaimed capital of Raqqa, with help from US airstrikes.

Facebook Twitter Pinterest Kurdish Peshmerga forces survey the positions of the Isis northeast of Mosul, Iraq in October, 2016. Photograph: Marko Drobnjakovic/AP

Other foreign backers of the opposition are not expected to be in Astana. Syria’s deputy foreign minister reportedly said last week that Saudi and Qatari attendance would be discussed only once they stopped backing militancy.

Why Kazakhstan?

Previous rounds of peace talks have been held in Geneva under the auspices of the UN. They were a conspicuous failure, producing little more than vague promises that were easily jettisoned and ceasefires that were rapidly broken. The new venue, Astana, reflects both the shift in powers trying to broker the talks, and hopes for a fresh start to efforts to find a negotiated end to Syria’s trauma.

Could this be the beginning of the end of the war?

Unfortunately it’s extremely unlikely that these talks will be anything more than a tiny step towards a negotiating process, even if all parties attending them agree they have been a success.

There is no clarity about what the groups are hoping to achieve, beyond an extension of the ceasefire, which will help save lives in the short term but cannot resolve the wider problems underlying the conflict.

If they can make progress towards the outline of a deal, the absence of two of the most influential opposition groups and the Kurds leaves huge questions about how it would actually play out on the ground.

Nor would peace mean the end of Syria’s refugee crisis. The brutality of the Assad regime precipitated the violence, and while all sides have committed atrocities, his forces and allies are responsible for the vast majority of civilian casualties to date.

Many of those who fled in fear of his militias or secret police will not be willing to return to a state ruled by Assad or his allies, known to persecute, torture and murder their opponents.

And finally, hanging over any vision of a new Syria that can be hammered out by Assad and his opposition is the spectre of Isis – determined to fight, well equipped and eager to die.