The Syrian government forces have advanced in the mountains of the northwestern province of Latakia, exposing supply lines connecting Latakia with the rebel-held nearby Idlib province, a monitor group reported.
The Syrian army advanced on Wednesday in northern Latakia, capturing the key hilltop of Hidadeh, near the administrative borders of Idlib, large swathes of which have fallen to the al-Qaida-linked Nusra Front and the so-called Conquer Army.
By capturing Hidadeh, the Syrian army has exposed the roads connecting the al-Akrad Mountains in Latakia with the Jisr al-Shughour area in Idlib.
Over the past months, the Syrian army achieved huge gains against the rebels in the northern countryside of Latakia.
A military source said the eye will be later on Idlib.
Separately Wednesday, the Syrian air force struck positions of the Islamic State (IS) group in the city of Deir al-Zour in eastern Syria, killing over 20 of them, state news agency SANA reported.
Also in Deir al-Zour, Russian cargo planes dropped over 10 parachutes containing food stuffs to the people in districts besieged by the IS in that oil-rich city near the Iraqi border.
To the south, in the Daraa province, the Syrian army killed over 15 militants with the Nusra Front in the town of Naimeh in the eastern countryside of Daraa.
Speaking of Nusra, the terror-designated group admitted Wednesday that one of its commanders, known as Abu Asil, was killed during battles with the Syrian army in the town of Hur-Binafsuh in the southern countryside of Hama province in central Syria.
Asil was responsible for waging several attacks on Syrian army positions in southern Hama.
Meanwhile, battles continued between the Syrian army and the IS militants in the al-Shaer gas field in the eastern countryside of the central province of Homs, reports said.
The Syrian army is fighting hard to recapture the field, which has fallen to the IS, when its militants unleashed a wide-scale offensive earlier this week in their quest to control gas and oil fields in Syria.
The Syrian forces' push toward the gas field was taking place on Wednesday under Russian air cover amid reports that the military forces are working to cut the IS supply lines east of the field.
The Observatory said the army was advancing around al-Shaer. It added that airstrikes were carried out Wednesday against the rebel-held city of al-Rastan in Homs countryside, killing 11 people, most of who are from the same family.
It said the death toll could rise as many bodies are still under the rubble.
In the predominantly-Kurdish city of Qamishli in the northeastern province of al-Hasakah, the UK-based watchdog group said battles broke out between the Kurdish security forces, Assayish, and Syrian forces, during which at least one man was killed and three others wounded.
The tension erupted over a wrangle between Syrian soldiers and the Assayish.
According to the Observatory, some Syrian soldiers wanted to enter a school guarded by the Assayish fighters, who refused to allow them in, and the scuffle later developed into a battle with fire arms.
Also Wednesday, aid convoys entered the Syrian town of Harasta in the countryside of the capital Damascus for the first time in four years, according to the International Committee of the Red Cross (ICRC).
The convoy carries food, medicine and essentials for 10,000 people, said the ICRC.
Harasta was among the first areas near Damascus to fall in the quagmire of the civil conflict which erupted in 2011. As the crisis dragged on, the Syrian government forces laid siege on the town which has become one of the key bastions of the rebels east of Damascus.
Only a week earlier, the ICRC attempted to send aid into the besieged town of Daraya in western Damascus, but was denied entry at the last military checkpoint.
The ICRC then said it had obtained all approvals to enter the town, urging the authorities to grant access for the desperately needed food and medicines.
The ICRC said recently that 13.2 million people need immediate humanitarian assistance in Syria, of whom six million are children.
Now in its sixth year, the conflict in Syria is the largest and most complex humanitarian crisis in the world, with no end in sight, the ICRC said.