Russian warplanes conducted a number of airstrikes targeting rebel forces in Idlib province, close to the Syrian-Turkish border, according to reports in Syrian media, and Syria analysts, who cited videos purportedly recorded on the ground close to the attacks.
The airstrikes took place close to the towns of al-Kafeer and Babsqa, and targeted positions held by Ahrar al-Sham, and Jaysh al-Islam, according to the Syrian-regime affiliated al-Masdar news.
Syria analyst Charles Lister, a senior fellow at the Washington DC-based Middle East Institute, concurred on Twitter that Russian airstrikes had targeted rebel positions near Babsiqa.
Mohammed Alloush, the political leader of Jaysh al-Islam and a member of the opposition Higher Negotiations Committee, said that the airstrikes had targeted a rebel headquarters in the area, in a post also on Twitter.
Some early reports said that the aircraft responsible for the strikes may have entered briefly into Turkish airspace.
Idlib province is held almost entirely by an increasingly tense alliance of rebels and Islamist factions and is the largest remaining rebel bastion in Syria.
It is regularly targeted by Syrian regime and Russian bombardment.
Idlib city became the second provincial capital to fall from government control when it was captured in March 2015 by the Army of Conquest, an alliance led by former al-Qaeda affiliate al-Nusra Front, later known as Fateh al-Sham.
Despite a December ceasefire deal brokered by Turkey, which backs rebels fighting against Assad, and regime ally Russia, violence continues unabated on many fronts across Syria.
The Syrian conflict began when the Baath regime, in power since 1963 and led by President Bashar al-Assad, responded with military force to peaceful protests demanding democratic reforms during the 2011 Arab Spring wave of uprisings, triggering an armed rebellion fuelled by mass defections from the Syrian army.
According to independent monitors, hundreds of thousands of civilians have been killed in the war, mostly by the regime and its powerful allies, and millions have been displaced both inside and outside of Syria.