Syrian President Bashar al-Assad vowed on Sunday to "use force to eliminate terrorism".
"We will continue to defend the stability and territorial integrity of our country," he told the Acting President of the Republic of Abkhazia, reported Syria’s state news agency SANA.
"Along with our allies, we will be able to strike the terrorists and their backers," he added.
"The terrorists don’t represent the people or state institutions. They only represent the agencies that operate and back them," he remarked.
Meanwhile, Syrian Foreign Minister Bassam al-Sabbagh said the state will work on restoring security and stability and consolidating unity and sovereignty.
He held telephone talks with his United Arab Emirates, Jordanian and Venezuelan counterparts.
"We will continue our war on terrorism," he vowed.
"The attack by terrorist groups on Aleppo and Idlib has terrorized the people and obstructed all aspects of life and led to the massive displacement of people," he noted.
At least 25 people were killed in northwestern Syria in air strikes carried out by the Syrian government and Russia, the Syrian opposition-run rescue service known as the White Helmets said early on Monday.
Russian and Syrian jets struck the opposition-held city of Idlib in northern Syria on Sunday, military sources said, as Assad vowed to crush opposition fighters who had swept into Aleppo.
The army also said it had recaptured several towns that the opposition had overrun in recent days.
Residents said one attack hit a crowded residential area in the center of Idlib, the largest city in an opposition enclave near the Turkish border where around four million people live in makeshift tents and dwellings.
At least seven people were killed and dozens injured, according to rescuers at the scene. The Syrian army and its ally Russia say they target the hideouts of opposition groups and deny attacking civilians.
The opposition fighters are a coalition of Türkiye-backed mainstream secular armed groups along with Hayat Tahrir al-Sham.
The opposition seized control of all of Idlib province in recent days, the boldest assault for years in a civil war where front lines had largely been frozen since 2020.
They also swept into the city of Aleppo, east of Idlib, on Friday night, forcing the army to redeploy.
The Syrian army said dozens of its soldiers had been killed in the fighting in Aleppo.
Russian war bloggers reported on Sunday that Moscow had dismissed Sergei Kisel, the general in charge of its forces in Syria. Reuters has requested comment from the Russian defense ministry.
Inside Aleppo city, streets were mostly empty and many shops were closed on Sunday as scared residents stayed at home. There was still a heavy flow of civilians leaving the city, witnesses and residents said, according to Reuters.
The opposition gains came after Israel stepped up its strikes on Iranian bases in Syria and Iran-backed Hezbollah forces in Lebanon. Militias allied to Iran, led by Hezbollah, have had a strong presence in the Aleppo area.
The Syrian war, which has killed hundreds of thousands of people and displaced many millions, has ground on since 2011 with no formal end. Most heavy fighting halted years ago after Iran-backed militias and Russian air power helped Assad win control of all major cities.
Iranian Foreign Minister Abbas Araqchi, visiting Damascus on Sunday, said the situation in Syria was "difficult" but the Assad government would prevail.
