It would be evidence that weeks of intense bombardments by the Syrian military, including airstrikes, have failed to dislodge the opposition. Instead, fighting rages across the country in a 17-month civil war that shows no sign of ending soon.
The opposition offensives in Aleppo are led by a brigade made up mostly of army defectors who specialize in operating artillery and tanks, said Mohammed Saeed, an activist based in the city.
He said the first attacks began shortly before midnight on Thursday and lasted until Friday, when the “Brigade of Free Syrians” launched coordinated strikes on several security compounds in Aleppo.
“The new operations aim to strike at regime forces' centers and air bases throughout Aleppo [province],” Saeed said via Skype.
The Britain-based Syrian Observatory for Human Rights said one of Friday's targets was a compound in the Aleppo neighborhood of Zahraa, killing and wounding a number of troops. It gave no figures.
Saeed said opposition forces attacked four security buildings around Aleppo, using tanks, rocket launchers and machine guns.
The state-run news agency, SANA, claimed troops killed and wounded several gunmen in the clashes.
The opposition took parts of Aleppo, Syria's commercial capital, last month. Since then, government forces have been trying to recapture them. The opposition fighters also control much of the wider Aleppo province, including areas on the border with Turkey.
Activists estimate more than 20,000 people have been killed in the uprising against President Bashar al-Assad's regime.
Fighting all over Syria
There has been fighting all over Syria, including the capital, Damascus, showing that the opposition forces have a presence in main population centers, not just the outlying districts where they started.
The Observatory and the Local Coordination Committees, another activist group, reported clashes and shelling between troops and the opposition in other areas, including the southern province of Daraa, around Damascus and in the central region of Homs.
The Observatory reported heavy clashes inside the sprawling Abu Zuhour air base in the northwestern province of Idlib, saying that anti-government gunmen were advancing, storming officers' housing units. The clashes in and around Abu Zuhour air base have been going on for the past two days. The reports could not be confirmed independently.
Syrian opposition forces said they shot down a Russian-made MiG fighter jet over Idlib on Thursday.
Over the past month, the Syrian regime has been relying much more heavily on air power, escalating the fight with the opposition as its ground forces have been stretched thin fighting on many fronts. The military has conducted air raids on the northern regions of Idlib and Aleppo near Turkey as well as the eastern province of Deir el-Zour.
The increased use of air power is likely a factor in the high daily death tolls, which activists say have been averaging 100-250 lately.
In Geneva, the UN refugee agency reported a growing number of Syrians fleeing to Lebanon's eastern Bekaa Valley, near the Syrian border.
Agency spokesman Adrian Edwards said local authorities report about 2,200 people arrived there over the past week, almost double the weekly average. He told reporters on Friday in Geneva that another 400 Syrians are reaching northern Lebanon each week.
Edwards said Turkey has opened two more refugee camps for Syrians in the past week and is now hosting 80,410 people in 11 camps and schools in its border provinces.
In France, Foreign Minister Laurent Fabius warned that France would use military force if President Bashar Assad ever uses his chemical weapons. “Our response would be immediate and sharp as lightning,” Fabius said Friday on Europe-1 radio.
He suggested that France would not wait for UN permission for such a response. “Bacteriological and chemical weapons are of a different nature from ordinary arms,” he said. “We cannot tolerate that these weapons, whose fallout could spread, would be used.”
Last month, Syria threatened that if it has chemical and biological weapons, it would use them to face a foreign attack.
Meanwhile, the International Committee of the Red Cross said on Friday that Syrian civilians' living conditions are worsening dramatically as dozens are killed every day in the fighting and it is becoming harder to obtain food and other basic needs.
The independent agency, whose 50 aid workers in Syria are confined to Damascus because of the lack of security, has been unable to send out convoys with supplies for the past two weeks, ICRC spokesman Hicham Hassan said.
"The situation in many parts of Syria is currently edging towards irreversible deterioration. Assisting the fast-growing number of needy people is a top priority,” the ICRC said in a statement, adding that tens of thousands have been displaced in recent weeks and most are completely dependent on assistance.