The rebels control the ground in large parts of the north, but they have been unable to solidify their grip because they – and civilians in rebel-held regions – come under withering strikes from aircraft stationed at a number of military bases in the area.

The Taftanaz air base in Idlib province is the largest air base yet to be captured by the rebels. It is the biggest field in the north for helicopters the military uses both for strikes on rebels and for delivering supplies to government troops still in the north to avoid the danger of rebel attacks on the roads.

Shortly after they captured the Taftanaz field, rebels in the neighboring province of Aleppo intensified their assault on the Mannagh air base and the international airport of the city of Aleppo, which includes a military base. Rebels have been trying to capture the two sites since last week, along with a third airfield known as Kweires.

The latest fighting came as international envoy Lakhdar Brahimi expressed little hope for a political solution for Syria’s nearly 2-year-old civil war anytime soon after meeting Friday with senior Russian and U.S. diplomats at the United Nations’ European headquarters.

Brahimi, who is the joint U.N.-Arab League envoy for Syria, met with Russian Deputy Foreign Minister Mikhail Bogdanov and U.S. Deputy Secretary of State William Burns. The talks were part of his attempts to find some traction for an international peace place calling for creation of a new, provisional government in Damascus that has so far gone nowhere.

Brahimi spoke with Assad in late December about the plan during a visit to the Syrian capital. Days afterward, Assad went on state TV with a defiant speech and a plan of his own, offering to oversee a national conciliation conference while rejecting any talks with the armed opposition and vowing to continue fighting them.

The speech was widely condemned, though Russia, one of Assad’s closest allies, said elements of it should be considered. Russia, along with China, has used its veto at the U.N. Security Council to shield its last Mideast ally from international sanctions.

“We are very, very deeply aware of the immense suffering of the Syrian people, which has gone on for far too long,” Brahimi told reporters after his talks in Geneva on Friday. “And we all stressed the need for a speedy end to the bloodshed, to the destruction and all forms of violence in Syria.

But if you are asking me whether a solution is around the corner, I’m not sure that is the case,” he said.

In Washington, State Department spokeswoman Victoria Nuland said Brahimi’s talks Friday produced “some progress” but that more work was needed. Asked to see where views between the U.S. and Russia converged, she said all parties support the idea of a transitional government that would be agreed to by the regime and Syrian opposition, and would have full executive powers.

“I’m obviously going to let the Russians speak for themselves, but it’s hard to imagine how you would have a transitional government with Assad still part of it,” Nuland told reporters.

More than 60,000 people have been killed since March 2011 in Syria’s conflict, which has turned into an outright civil war driving hundreds of thousands from their homes and across the borders into neighboring countries.

Neither side has been able to gain a decisive military edge. But the capture of Taftanaz showed the creeping progress of rebels in the pocket of northwest Syria where they have been trying to solidify their control.

The fall of the base is a new embarrassment for the regime, a sign of its fraying hold in the north. It also provides a strong boost for the arsenal of the rebels, who partially rely on weapons looted from the military.

It chips away at the regime’s air power in the north, but is far from eliminating it. There remain several other, smaller helicopter bases, and regime warplanes that also strike the area operate from bases further south. The capture wouldn’t affect the military’s airpower against rebels in other parts of the country.

“It is a moral blow but will not change the reality on the ground,” said Hisham Jaber, a retired Lebanese army general who heads the Beirut-based think tank Middle East Center for Studies and Public Relations. He noted the regime has more than a dozen military bases around the country.

The battle also showed the strength of Islamic militants in the rebel ranks. The assault on Taftanaz was carried out by fighters from Jabhat al-Nusra, an al-Qaida-affiliated group that includes many non-Syrian jihadis, and by other Syrian brigades with a similar hard-line Islamist ideology.

Fighters from Jabhat al-Nusra, which the U.S. has branded a terrorist organization, have been among the most effective in the rebel ranks.

They launched their siege of the sprawling base in November and finally broke into it Wednesday evening. After fierce fighting lasting until dawn, they swept over the entire facility.

“As of now, the rebels are in full control of the air base,” said Idlib-based activist Mohammad Kanaan.

After sunset, troops bombarded Taftanaz with artillery from nearby areas, according to the Syrian Observatory for Human Rights, a Britain-based anti-Assad activist group that gathers information from operatives on the ground. Rebels have been forced to abandon previous bases they have captured because they are too exposed to regime strikes.

But, as in previous captures of smaller bases, weapons were the key prize.

Video taken by activists inside the base and posted online showed rebels dismantling ammunition from a heavy machine gun in the base and loading the ammunition into a truck. In other videos, rebels are seen celebrating inside the base, some kneeling and kissing the ground and others showing off booty including multiple rocket launchers. Kanaan said tanks were also captured.

The videos appeared genuine and corresponded to other AP reporting on the events depicted.

One video showed helicopters in the field, some destroyed, some seemingly intact. It was not clear whether any were operable. The Observatory said around 20 helicopters were seized but none were in working order. Rebels have seized helicopters in the past but there’s been no reported case of them flying one.

“These are the helicopters that belonged to Assad’s regime and now they are the helicopters of the Syrian people,” said the video’s narrator, who spoke with an Arabic accent indicating he was from North Africa.

In one video, at least six dead men in military uniform were seen on the ground outside one of the housing units in the base. Two other dead men were seen inside the building. “They refused to defect. We have been urging them to defect since our attack began 10 days ago,” the rebel narrating the video said.

Another video released by the Observatory showed at least four dead men in uniform, including two in pilots’ uniforms, in what appeared to be a trench.

There was no immediate word on casualties among rebels.

Until the fall of Taftanaz, the biggest capture had been that of the Marj al-Sultan base just outside the capital Damascus. The base was mostly used for fixing helicopters but the rebels captured several choppers in it.

Also Friday, a car bomb killed one person in Damascus, activists and state media said. The Observatory said the dead man was a police general, while state-run news agency SANA said the dead was a civilian.

Rebels said Friday that a senior rebel commander was gunned down this week by rival fighters in northern Syria.

Thaer al-Waqqas, a northern commander with the al-Farouq Brigades, was shot dead at a rebel-held position in the town of Sarmada, near the Turkish border Wednesday. A rebel, speaking on condition of anonymity because of the sensitivity of the incident, said al-Waqqas had been wanted by the al-Qaida affiliated Jabhat al-Nusra group for suspected involvement in the September killing of Sheikh Firas al-Absi, a member of the group.

There are dozens of opposition groups and rebel brigades fighting in the civil war and the killings raised the specter of infighting between rebels seeking to topple Assad. Rivalries are common and there have been several several instances of rebels fighting each other over ideological and other differences.

Al-Farouk brigades, in a posting on its website, said al-Waqqas was killed by “the gangs of treachery and treason who claim to be fighting under the banner of the revolution.”

It vowed to revenge his killing.