Anti-regime fighters and their allies blocked the Damascus-Aleppo highway on Thursday during an offensive that reportedly left around 200 dead, including civilians targeted by Russian airstrikes, according to a monitor.
A day earlier, Hayat Tahrir al-Sham (HTS) and allied factions launched a surprise attack on regime-held areas of northern Aleppo province, triggering the fiercest fighting in years, the Syrian Observatory for Human Rights said.
The toll in ongoing battles "has risen to 182, including 102 fighters from HTS", 19 from allied factions "and 61 regime forces and allied groups", said the Observatory.
"Russian air strikes on the Aleppo countryside killed 19 civilians on Thursday," said Rami Abdel Rahman, who heads the Observatory, adding that another civilian had been killed in Syrian army shelling a day earlier.
Russia is a close ally of Syrian President Bashar Assad and first intervened in Syria's civil war in 2015, turning the momentum of the conflict in favor of the president, whose forces once only controlled a fifth of the country.
HTS and its allied factions "cut off the Damascus-Aleppo international M5 highway... in addition to controlling the junction between the M4 and M5 highways," said the Britain-based monitor.
"The highway has now been put out of service after it was reopened by regime forces years ago," said the monitor, which has a network of sources inside Syria.
The junction of the M5 and M4 highways connects the capital and regime coastal stronghold Latakia with the second city Aleppo respectively.
Syria has been gripped by civil war for more than a decade, although the intensity of the conflict has decreased in recent years.
Some of the clashes, which are happening in an area straddling Idlib and Aleppo provinces, are less than 10 kilometers (six miles) southwest of the outskirts of Aleppo city.
"This operation aims to repel the sources of fire of the criminal enemy from the frontlines," said Mohamed Bashir, who heads HTS's so-called "Salvation Government," during a news conference.
Analyst Nick Heras of the New Lines Institute for Strategy and Policy said the opposition were "trying to preempt the possibility of a Syrian military campaign in the region of Aleppo, which Russian and Syrian government airstrikes against rebel areas has been preparing for."
With some Türkiye-backed factions joining the offensive, he said "Ankara is sending a message to both Damascus and Moscow to back down from their military efforts in northwest Syria," he said.
Opposition forces "are in a better position to take and seize villages than Russian-backed Syrian regime forces, while the Iranians are focused on Lebanon," Heras said.
Analyst Haid Haid said the opposition had been "planning for this offensive for quite a while."
But "if the rebel forces waited too long the regime would have been able to reinforce their frontlines as Hezbollah forces are no longer busy with the war in Lebanon."
HTS controls swathes of the northwest Idlib area as well as small parts of neighboring Aleppo, Hama and Latakia provinces.
A Turkish defense ministry source said Türkiye was following developments in northern Syria closely and had taken precautions to ensure the security of Turkish troops there.
On Thursday, Turkish security sources said tensions have already been brewing between regime forces and militant groups, referring to HTS. Sources said Türkiye's direct intervention prevented regime forces and militants from taking over Idlib in its entirety in the period between 2019 and 2020 when the regime's operations worsened the situation for its opponents, changing the border agreed upon in talks sponsored by Türkiye, Iran and Russia. Sources said Russia and the Assad regime repeatedly carried out attacks toward Idlib and all sides claimed they launched attacks to prevent military buildup in the area.
Sources said Türkiye prevented operations by opposition groups until today so as not to escalate tensions further in the region amid Israel's aggression. "Türkiye also pursued international efforts and conveyed its expectations to prevent attacks by the Assad regime to guarantor countries in Astana and other platforms. Yet, international platforms did not take any steps to that extent," the sources said. They cited that more than 30 civilians were killed in attacks targeting Idlib, including three children attending Quran school.
HTS competes with more mainstream opposition groups backed by Türkiye that also control swathes of territory along the Turkish border.
