Latest escalation comes amid increased Turkish military involvement in a region stretching from Syria to the Caucasus and the Mediterranean.
Russia and Turkey are two sides of the same coin. They are both heavily involved in some of the world’s most significant ongoing conflicts including in Libya, the Caucasus and Syria.
They remain at loggerheads, supporting opposing sides with both hoping to expand their military presence and political reach in the Middle East and the Mediterranean.
Though both countries are also waging proxy battles, it is rare to see them come head-to-head.
But a deadly Russian air strike that took out dozens of Turkish-backed rebel fighters in northwest Syria on Monday has marked a significant escalation.
Observers say the attack in the Jabal al-Dweila area, which targeted a military training camp for Failaq al-Sham, one of the largest Turkey-backed armed groups in the area, was a “message” to Ankara.
As Turkey’s closest proxy in Idlib province, this “wasn’t a Russian attack on the Syrian opposition as much as it was a direct hit against – and message to – Turkey”, Charles Lister, director of the US-based Middle East Institute, told Al Jazeera.
Given the “enormity” of the attack, which killed at least 35 fighters and wounded more than 50, Lister said it is possible that wider geopolitics may have pushed Russia to strike.
Though Russia – a staunch ally of Syrian President Bashar al-Assad – and Turkey negotiated a fragile ceasefire in Idlib, which largely held since March this year, the latest escalation points to signs of strain over Turkey’s involvement in various battles.
Most notably, in the Caucasus, where Ankara has declared support for Azerbaijan in its fight against Armenia in the disputed Nagorno-Karabakh region.
Moscow, traditionally closer to Armenia, has voiced dismay at reports indicating Syrian mercenaries have been sent to fight alongside Azerbaijani forces – opening up a new front in the proxy standoff.
And in Libya, thousands of Syrian fighters have been reportedly sent by Turkey over the past year to fight on behalf of the United Nations-recognised Government of National Accord in Tripoli, which is fighting Russian-backed forces.
But in Syria, although they support opposite sides in the country’s nine-year conflict, Moscow and Ankara have worked together to maintain a ceasefire in the last rebel-held enclave in the northwest.
Earlier this year, they brokered a truce in Idlib to halt a government offensive that displaced nearly one million people, in one of the worst humanitarian crises of Syria’s nine-year war.
Of those displaced in the offensive, more than 200,000 have returned home to their towns and villages, most since the ceasefire went into force.
But the truce in Idlib, a war-battered province that is home to more than three million people, has remained fragile with intermittent bombardment in the area from both sides.
‘Radical’ groups in Idlib
Other experts including Turkish columnist Semih Idiz agree the timing of the Russian air strike is “significant” at a time when Ankara is “flexing its muscles” in the Middle East and the Caucasus.
“The Armenian-Azeri dispute is a particularly sensitive issue because it is happening in what Moscow believes is its backyard and sphere of influence,” Idiz told Al Jazeera.
But Idiz said other reasons may have led to the strike, such as Ankara’s inability to solve the issue of groups in Idlib that Moscow perceives as “radical”.
The Turkish-backed National Liberation Front alliance includes 11 Free Syrian Army (FSA) factions all supported by Ankara. But it excludes Hay’et Tahrir al-Sham (HTS), a former al-Qaeda affiliate that currently controls large swaths of the province.
When the first major Idlib deal was signed by Russia and Turkey in 2017, a main condition set forth by Moscow was that Ankara must dissolve HTS. Russia has often used the presence of Tahrir al-Sham to attack Idlib.
But Turkey has not done away with the armed group either because it cannot, or does not want to, Idiz said.
“This latest strike is Russia’s way of saying that time is running out – or has run out,” he said, referring to the conditions set in a deal agreed on by Russian President Vladimir Putin and his Turkish counterpart Recep Tayyip Erdogan at a summit earlier this year.
Dareen Khalifa, a senior Syria analyst at the International Crisis Group, agreed, noting the need to target certain rebel groups is a justification Moscow will continue to use.
“This kind of escalation is consistent with Moscow’s approach towards the ceasefires that have been governing Idlib,” Khalifa told Al Jazeera.
“The deal, like its predecessors, is inherently flawed as it is built around the premise that Turkey would go after some of the strongest rebel formations in the area,” she said.
If any ceasefire is to last, Moscow and Ankara must first address the “gap between their respective positions”, Khalifa said, namely how to deal with some of the rebel groups in Idlib, including HTS.
Previous attacks by Russia in the area were intended to push opposition fighters away from the key M4 highway in northern Syria, where Turkish and Russian forces often conducted joint patrols as part of the truce agreement.
In recent months, however, joint patrols have come to a halt, making an escalation more plausible.
The patrols achieved little in practical terms, according to Idiz. They only “give the impression of cooperation between Turkey and Russia”.
“Halting these patrols is a clear indication that the ceasefire agreement … is gradually being eroded, leaving only the military option on the table again,” he said.
It is unlikely though, that Ankara will choose to personally retaliate over Monday’s deadly strike.
Lister said a significant escalation at this time is doubtful but noted it is difficult to expect that Ankara will “let this slide altogether”.
Meanwhile, Idiz said Turkey may want to “take it out” on Syrian President Bashar al-Assad’s forces allied with Russia.
On Tuesday, a day after the attack, Syrian opposition fighters fired hundreds of missiles and artillery shells at government posts in northwest Syria.
“If one of those hits a sensitive pro-regime target, or if such attacks sustain themselves, we could easily see a tit-for-tat become an uncontrollable spiral back into hostilities,” Lister said.
A renewed, full-fledged offensive would be catastrophic for the province’s battle-weary residents, now facing a devastating coronavirus crisis and the onset of another winter.
Many of the displaced have amassed in already overcrowded camps near the border with Turkey, and have limited access to basic supplies, including clean running water.
But as long as Idlib’s future is “hinging on Russian-Turkish regional calculations”, the areas in northwestern Syria will continue to be used as “bargaining chips”, Khalifa warned.