The Syrian war could still be raging in four years' time unless the US and Russia agree to end it

“Will the war in Syria ever end?” After seven years of conflict, the same question is being asked by politicians, diplomats, fighters in the front line, and families cowering in unlit basements to escape devastating bombardments from Ghouta to Afrin.

When I asked Aldar Khalil, a top Syrian Kurdish leader whose forces control a quarter of Syria, about the chances of peace in an interview in north-east Syria, he grimly but confidently predicted that the war would go on “for another four years, until a new balance of forces becomes clear”.

We must speak of multiple armed conflicts in Syria rather than a single war so that when one military confrontation gets close to its final chapter, it is swiftly replaced by another. Isis, the greatest threat of 2014 to 2017, is largely eliminated, but the new focus of violence is the escalating struggle between Turkey and the two or three million Syrian Kurds.

The Syrian Army is advancing into Eastern Ghouta and the likelihood is that President Bashar al-Assad will soon have almost complete control of the capital for the first time since 2012. One outcome could be for the rebel fighters to leave with light weapons for opposition or Turkish-held territory in southern and northern Syria, while the bulk of the civilian population would be amnestied and stay where they are. But the Syrian war is littered with compromise solutions which never quite came about because there were too many players to agree on a common course of action.

One siege may be ending in Eastern Ghouta, but another is beginning 200 miles to the north in the Kurdish enclave of Afrin. The Turkish army and its Arab auxiliaries describing themselves as the Free Syrian Army, but, going by their own videos much closer to Isis and al-Qaeda, say they have surrounded the city. It will ultimately fall but it is unclear if the 10,000 Kurdish fighters there will fight to the death. If they do make a last stand, then Afrin will join the many other Syrian cities which have been reduced to rubble.

In the sieges of East Aleppo and Eastern Ghouta, there was a propaganda advantage to the opposition in holding out for as long as they could because of the international outcry against the Syrian army and government. But foreign states and the international media are largely ignoring atrocities in Afrin that would get wall-to-wall coverage if were happening in Eastern Ghouta.

For the Kurds, there are no good options in Afrin, though it might be better from their point of view not to resist to the bitter end in the hope that this would avoid the city being pounded to pieces, as has happened so often elsewhere.

In Afrin, the Kurds have no foreign allies to come to their rescue as occurred during the famous siege of Kobane by Isis in 2014-2015. The US said that it never had an interest in the enclave and the Russians, whose planes and anti-aircraft missiles control the skies over north-west Syria, have evidently agreed that Turkey should take Afrin. The reasons behind this decision illustrate how great power rivalries are fuelling the war in Syria and stop it coming to an end.

Advantages for the Russians include bringing Turkey into permanent conflict with the US, which is allied to the Kurds in the great swathe of territory they control thanks to US backing east of the Euphrates River. The Russians may also want to teach the Kurds a lesson for putting all their eggs in the American basket, not that the Kurds have much choice. They cannot hope to defend the open plains of north east Syria without the threat of a devastating air strike by the US.

The Kurds have a well-developed sense of victimhood and live in fear of once more being betrayed by their great power allies. But, for good self-interested reasons that have little to do with US gratitude to the Kurds for their role in the defeat of Isis, Washington is unlikely to run away from its alliance with the Kurds, at least for the moment. The US needs them as a force on the ground to back up its air power if it is to remain a player in Syria. The alternative is to accept a Russian victory in the country. As the last seven years have shown, the only possible force capable of fulfilling this role is the Kurdish YPG.

The Russians, for their part, know that it was their military intervention in Syria which in a single stroke restored their status as a superpower or something like it, a position they had lost when the Soviet Union disintegrated in 1991. When the Syrian crisis first exploded in 2011, a senior Iraqi official asked an American general what was so different between the situation in Libya, where Gaddafi had just been ousted and killed, and that in Syria. The general replied in a short succinct sentence, saying that in Syria “Russia is back”.

The rivalry of great and regional powers is fuelling the Syrian wars and preventing them coming to an end. But, paradoxically, the US and Russia also present the best chance of bringing these savage conflicts to an end. They alone are the heavy hitters with enough political and military muscle to push the regional and local players towards a compromise peace.

But we have not reached that stage yet when everybody feels there is nothing left to fight for and clear winners and losers have emerged on the battlefield. It is true that some issues have been decided: President Bashar al-Assad will stay in power and he already controls about 12 million of the 16 million Syrians still in the country. After recapturing Eastern Ghouta, he will control all of Damascus and Aleppo as well as almost all the other cities. He may well feel that he is on his way to achieving his ambition to retake the whole of Syria, however long it may take.

But control of the great powers is not absolute: commentators often mistakenly imagine that local proxies in Syria and Iraq are more obedient to their sponsors than they really are. This can be true when the proxies are under intense political or military pressure, but otherwise they resent too close compliance to the orders of their outside backers whose interests frequently diverge from their own. To adapt the American definition of statesman – “a statesman is a politician who stays bought” – no party in Syria and Iraq stays bought, if they can possibly avoid it.

It is easy to describe the wars in Syria in terms realpolitik, but it is wrong to believe that the ongoing turmoil can be controlled by anybody. The players and wildcards are too many for this to happen. Syria is often described as “a quagmire”, but it is more useful to picture it as a great poisonous stew in which the ingredients are contending sects, ethnicities and foreign powers that continually produce new and lethal combinations. In these circumstances, Aldar Khalil’s forecast of another four years of war begins to sound almost optimistic.