President Bashar al-Assad's government has repeatedly criticised Turkey's operation in Syria, which saw Ankara in late August send troops across the border where they are working with local rebels.
Turkey's invasion has also been fiercely opposed by the US-backed Syrian Democratic Forces, which is dominated by Kurdish fighters.
"For the government, just as for the Syrian Kurds, the enemy is (Turkish President Recep Tayyip) Erdogan. They want to counter his project of invading the border territory," said Waddah Abed Rabbo, editor-in-chief of Syria's Al-Watan daily.
"It's completely normal that the forces present on the ground would ally with each other to block any Turkish advance in Syrian territory. Now, Turkish forces are totally encircled," said Abed Rabbo, whose paper is close to the government.
With help from Turkish air strikes, artillery, and soldiers, Syrian rebels last week overran the town of Al-Bab, the Islamic State group's last bastion in the northern province of Aleppo.
Syrian troops had advanced to the southern edges of the town, but had been ordered by their ally Russia not to enter Al-Bab after Moscow struck a deal with Ankara.
Instead, regime fighters headed east, sweeping across previously IS-held villages to link up with the SDF south of its stronghold in Manbij.
'Surrounded on all sides'
In just 15 days, Assad's army seized nearly two dozen villages, including Taduf south of Al-Bab, gaining approximately 600 square kilometres (230 square miles) of territory in Aleppo province.
The advance brought Syrian troops to territory just southwest of Manbij and adjacent to SDF forces there, said US-based Middle East expert Fabrice Balanche.
By sealing off that territory, Balanche added, the regime has stemmed Turkish ambitions of heading further east.
"The road to Raqa via Al-Bab is now cut for the Turks. They also can't attack Manbij from the south," Balanche added.
Erdogan has insisted that Ankara wants to work with its allies to capture Raqa, the de facto Syrian capital of IS's so-called "caliphate", without the SDF.
Turkey considers the SDF's biggest component -- the Kurdish People's Protection Units (YPG) -- as "terrorists" because of their links to an outlawed Kurdish militia in southeast Turkey.
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But the SDF has a head start. Since November, it has been battling to encircle Raqa with the help of US-led coalition air strikes and is much closer to the city than the Turkish-backed fighters.
The regime's recent advance has boxed Turkey in, according to the Syrian Observatory for Human Rights monitoring group.
"They're surrounded on all sides. The Kurds are to the east, southeast, and west. The regime is south," said Observatory head Rami Abdel Rahman.
"They don't have a single road to Raqa except via territory controlled by the Kurds or the Syrian army," Abdel Rahman said.
'Regime has not changed'
"If they really want to go, they only have two options: opening up a front with the army or the Kurds, or striking a deal with them."
Such a deal would require the mediation of either Russia -- who has long backed the Syrian regime and has recently developed closer cooperation with Turkey on Syria -- or the United States, an ally to Ankara and SDF backer.
"The risk of confrontation is there. But if the Turkish army heads towards Raqa, it will only be after a deal with the United States," said Sinan Ulgan, who heads the Centre for Economics and Foreign Policy (EDAM) in Istanbul.
While the SDF and Syria's regime have a shared interest in countering Ankara's influence, the alliance is not foolproof.
Regime forces and Kurdish fighters have clashed several times across the northeastern province of Hasakeh, and government officials frequently criticise a Kurdish announcement last year of a "federal system" to run affairs in northern Syria.
"The regime is against Kurdish independence, but it doesn't have the means to retake Kurdish territory," Balanche said.
A high-level security source in Damascus insisted that "Syria does not recognise the SDF because the constitution stipulates that the only military presence in Syria is the Syrian army."
"But really, there are several legitimate and illegitimate organisations involved in the Syrian conflict," the source conceded.
Leading SDF adviser Nasser al-Hajj Mansour denied that his group had struck a deal with the regime, but acknowledged that the current situation is an incentive for cooperation over confrontation.
"The regime has not changed. When it can, it will attack us. But today, local and international dynamics will not allow it to do so," he said.