Russian and Syrian jets hammered a major jihadist stronghold on Tuesday, days before leaders of Russia, Iran and Turkey meet to discuss an expected Syrian government operation.
The airstrikes hit several areas held by the jihadist-led Hayat Tahrir al-Sham alliance, but also areas held by Turkish-backed jihadists, including the town of Ariha, AFP says.
The province in the northwest of Syria is the last remaining stronghold of armed groups in the country, including Nusra Front terrorist organization. Idlib's dominant terrorist faction is Tahrir al-Sham, a jihadist alliance spearheaded by al Qaeda's official affiliate in Syria, the Nusra Front.
Russian air raids ceased in and around Idlib on Aug. 15, but Syrian army has maintained an aerial bombardment and shelling there, Syrian Observatory for Human Rights (SOHR) said.
The Syrian army has been preparing for a full-scale military operation.
Turkish AKP government, which has backed some jihadists against the Syrian government, has previously said that a military operation into Idlib would be disastrous.
Tuesday's airstrikes came hours after U.S. President Donald Trump warned Syrian President Bashar al-Assad and his allies not to "recklessly attack" Idlib, saying that hundreds of thousands might die.
Russia says militants in Idlib target its own facilities in Syria and pose a terrorist threat.
The Kremlin dismissed Trump's comments, describing Idlib, where jihadist groups dominate, as a "nest of terrorism". Spokesman Dmitry Peskov added: "We know that Syria's armed forces are preparing to resolve this problem."
Peskov said such warnings do not consider "the dangerous and negative potential" of the jihadist-held enclave and show that the White House does not have a "comprehensive approach" to solving the Syria crisis.
The presidents of Turkey, Russia and Iran are to meet in Tehran on Friday for three-way talks that are expected to focus on Idlib.
A Syrian government minister said the liberation of Idlib would probably be resolved by force. "Until now, military action is more likely than reconciliations," Reconciliation Minister Ali Haidar told Russia's Arabic-language Sputnik news agency.
"Idlib differs from other areas in that there are many militants, this is their last resort, and Turkey is trying to keep Idlib to itself ... In other areas, the work moved along in two main directions, ceasefires and a military solution, this is the basis that there was, but at the moment, the military operation seems more likely than a ceasefire due to the aforementioned reasons," the minister said.