Syrian opposition fighters captured a military airport near the northern city of Aleppo on Tuesday in another military setback for President Bashar al-Assad's forces which have come under intensifying attack across the country.
The airport is the latest military facility to fall under rebel control in a strategic region situated between Syria's industrial and commercial centre and the country's oil- and wheat- producing heartland to the east.
Fighting in the nearly two-year-old conflict has intensified in the three weeks since the political leadership of the opposition offered to negotiate a departure for Assad.
In the first direct government response, Syria's minister for "national reconciliation", Ali Haidar, said he was willing to travel abroad to meet Moaz Alkhatib, the Cairo-based president of the Syrian National Coalition opposition group.
Authorities had previously said they would talk to the "patriotic opposition" - figures who have not allied themselves with the armed rebellion. But most centrist opposition figures have left the country since Abdel-Aziz al-Khayyer, a proponent of dialogue and non-violence, was arrested last year.
"I am willing to meet Mr Khatib in any foreign city where I can go in order to discuss preparations for a national dialogue", Haidar told the Guardian newspaper.
But Haidar said the authorities rejected any dialogue that aims "to hand power from one side to another" and insisted that formal negotiation must take place on Syrian soil.
The main push for talks on a transition is coming from U.N. envoy Lakhdar Brahimi, a veteran diplomat who helped mediate an end to civil war in neighbouring Lebanon and warned that Syria could become a failed state.
With the minority Alawite sect, an offshoot of Shi'ite Islam, dominating power in Syria, the conflict has deepened the Shi'ite-Sunni divide in the Middle East.
Jets over Damascus
In the capital Damascus, residents and activists said the army had moved tanks to central Abbasid Square to shore up its defensive lines after rebels breached it last week and then struck several security targets in the heart of the capital.
Jets bombarded rebel held areas in the east of the capital and in an expanse of farmland and urban areas known as Eastern Ghouta, from where rebels have launched an attack to cut off the loyalist supply lines.
"The bombing has been terrible. The centre of Damascus is shaking. You can hear the jets from here," said one woman.
Despite a large military arsenal - opposition activists reported several Scud missiles being fired at unknown targets from an army base north of Damascus - Assad's forces appeared to be on the defensive in many parts of the country.
The army and a plethora of security forces remain entrenched in fortress-like bases in Damascus and the provincial capitals, where their advantages in air power and heavy weaponry have kept the opposition from taking over the major cities.
Jarrah air base, 60 km (40 miles) east of Aleppo, came under the control of rebel units who have been surrounding it for weeks, and the highway linking Aleppo to the east of the country is in opposition hands, the Sham News Network said.
Video footage showed fighters from the Islamic Free Syria Movement inspecting the airport. Several fighter jets were shown on the ground at the airport and in concrete shelters.
Abu Abdallah Minbij, one of the opposition commanders who planned the attack on the airport, said by phone that two operational MiG jets and ammunition were found intact at the base, along with 40 disused fighter jets.
"The airport was being used to bomb northern and eastern rural Aleppo. By capturing it, we have cut the regime's supply line from Aleppo to the east," Minbij said.
He said the army will now struggle to send reinforcements to stop a rebel advance in the adjacent Raqqa province, where rebels have captured the country's largest hydro-electric dam this week.
In Sfeira, a nearby town in rural Aleppo, footage showed opposition fighters surrounding a captured tank in the middle of the town, with the body of three soldiers on the ground.
Assad's father, the late President Hafez al-Assad, used carrot and stick tactics to build alliances with the Sunni Muslim tribes in rural Aleppo and in Raqqa and Deir al-Zor to the east that cemented the decades long domination of his Alawite minority on the country.
But most of the alliances between the ruling minorities have broken down since the 22-month uprising erupted in March 2011.
Opposition activists said Liwa al-Islam, the largest rebel unit in the area, has thousands of fighters belonging to tribes that have abandoned Assad, such as the Anzeh tribe, which extends to Saudi Arabia.
They said the focus of rebel operations in Aleppo the last few weeks have been to neutralise four airports in the province, including Jarrah, which have been also used as artillery bases to shell surrounding rebel-held countryside and towns.
"The airports have been a source of aerial bombardment and indiscriminate shelling on rural Aleppo and on the city itself," activist Abu Louay al-Halabi said by phone from Aleppo.
He said rebels have hit planes on the ground belonging to two squadrons based in the airport of Minbij, 70 km (45 miles) northeast of Aleppo and overran several buildings in Nairab airport, which is adjacent to the city and remains in government hands.
"Once the airports are neutralised, the opposition's grip on Aleppo will become less tenuous and the fighters can concentrate on taking the whole city," Halabi said.