What does Russia want in northwest Syria?

After months of heightened tensions in the Syrian province of Idlib, the last stronghold of the Syrian opposition, Russia and Turkey seem to have reached a temporary solution.

Following a meeting between Russian President Vladimir Putin and his Turkish counterpart, Recep Tayyip Erdogan, on September 17 in Sochi, the two countries agreed to create a demilitarised zone 15-20km into opposition-control territories along the de-facto front line by October 15.

All “radical fighters” are to withdraw from the area and all “heavy weapons, tanks, rocket launchers, guns and mortars” are to be removed. Russian military police and Turkish troops will be patrolling the zone to ensure that all armed groups abide by the agreement. Erdogan and Putin also agreed to open the M4 and M5 highways linking respectively Latakia and Damascus to Aleppo to traffic from regime-held areas by the end of the year.

Of course, this temporary truce is far from ideal and does not include a roadmap for normalisation of the situation in the province, but it is still better than all the other, more violent, options.

The main beneficiary of the deal is, of course, Ankara, but it is also in Moscow’s interest to de-escalate tensions. Despite its extremely militaristic rhetoric, Russia too wanted to avoid a large-scale offensive and most importantly, a potential military confrontation with Turkey.

That risk got that much higher when Ankara started deploying even more troops and heavy weaponry to the province earlier this month.

A large-scale military operation could have also led to another chemical attack, as the United Nations, the United States and Russia itself warned. This would have exposed Moscow to more criticism and scrutiny from the international community and institutions. Given the ongoing investigation into the Skripal poisoning in the UK, which has named two Russian intelligence agents as main suspects, the Kremlin wants to avoid another international scandal.

At the same time, while it’s in Russia and the Syrian government’s interest to destroy the armed opposition and capture Idlib, doing so would effectively mean the end of the Astana process. As a result, the Kremlin would lose an important platform for legitimising its presence in Syria and for engaging with Turkey. Moscow has sought closer relations with Ankara not only to secure major energy projects but also to use them as leverage against the European Union and the US.

Capturing Idlib would also bring a military solution to the Syrian crisis, which would automatically remove Russia from its position as kingmaker in Syria. In any further political negotiations, Russia’s military presence in Syria would no longer have much leverage value, as talks would focus on funding and reconstruction – two areas where Moscow feels extremely insecure and unable to offer much.

Although, for now, a demilitarised zone in Idlib seems to be in the interest of both Russia and Turkey, there are no guarantees that it will be implemented. Both will now have to convince their partners on the ground to submit to this arrangement and it is not clear whether the Syrian government or the Syrian opposition (especially the “radical elements” within it) would agree to it. This means that the likelihood of a large-scale military operation in Idlib remains extremely high

Syrian President Bashar al-Assad is still determined to regain control over Idlib and the forces loyal to him were bombing the opposition in Idlib until last week. After this year’s victories in the Damascus suburb of Eastern Ghouta and in the southern provinces of Deraa and Quneitra, he no doubt wants to keep the momentum going and attack Idlib. The question for Damascus was never whether it should attack the opposition stronghold in the northwest or not, but when it should do so.

On the other side, it is unclear whether the opposition would agree to disengage and disarm, especially the “radical” part of it – i.e. the former al-Qaeda affiliate Hay’et Tahrir al-Sham (HTS).

Even if Turkey is able to convince HTS and other “radical” groups to withdraw from the demilitarised zone, it might have trouble securing the M4 and M5 highways. About 200km of both roads run through opposition-controlled areas, which would not be included in the demilitarised zone. Turkey is likely to face major challenges ensuring that there are no attacks or robberies by armed groups once the highways are opened to traffic from regime-held areas.

If Turkey ends up having to launch a military operation against HTS to contain it, it will face another challenge: obtaining permission from Russia to use Syria’s airspace for its fighter jets. During the Afrin operation, Moscow initially allowed the Turkish air force to operate above Afrin and then disallowed it. For the Kremlin, this is a matter of principle: once it loses control over Idlib’s airspace, it risks not being able to get it back. With no air cover, Turkey’s military operation would face major difficulties and the process of disengagement, in general, would seriously falter.

In the end, even if the demilitarised zone is successfully implemented, it would only be a temporary solution to the problem of Idlib’s future status. Moscow made a gesture of goodwill to Ankara but it also has transferred responsibility for what happens next in the province to its Turkish partner. The majority of the work to implement and maintain this agreement will fall on Turkey’s shoulders.

How long the deal will hold and whether Russia indeed has put on hold its plans for an Idlib offensive will become clear in the following few weeks.

The views expressed in this article are the author’s own and do not necessarily reflect Al Jazeera’s editorial stance.