A Syrian mother and her two children walk through the mud after the first snow of the year fell the previous night at a refugee camp in Bab al-Salam on the Syria-Turkey border, on Wednesday, January 9. Click through to view images from the Syrian conflict from December and January, or see photos from November.
A Syrian boy walks near rubbish next to tents at a refugee camp near the northern city of Azaz on the Syria-Turkey border, home to more than 7,000 people mostly from the northern districts of Aleppo and Marea, on Tuesday, January 8.
Syrians look for survivors amongst the rubble of a building targeted by a missile in the al-Mashhad neighborhood of Aleppo on Monday, January 7.
A rebel fighter, right, prepares the wires of a car-mounted camera to spy on Syrian government forces in Aleppo's Old City on January 7.
TV monitors broadcast the live feed from a camera on a car that rebels use to monitor government forces in Aleppo on January 7.
Syrians search for survivors in the rubble of a building targeted by a missile in Aleppo on January 7.
Syrians walk through debris in Aleppo after a missile hit a building January 7.
A teen rebel fighter runs behind a makeshift barrier in Aleppo on Sunday, January 6, while snipers loyal to the government monitor the street.
Smoke rises after what activists said was shelling by forces loyal to Syrian President Bashar al-Assad in Deir Al-Zor on Friday, January 4.
A resident reacts to the death of two of his children who activists said were killed during shelling by forces loyal to Syria's President Bashar al-Assad in the al-Ansari area of Aleppo on Thursday, January 3.
Syrians carry the body of a victim who activists said was killed during the bombing in the al-Ansari area of Aleppo, January 3.
A street is filled with debris after fighting between Syrian government forces and rebels in Aleppo on January 3.
Rebel fighters inspect the debris on a street in the Bustan al-Basha district in the Syrian city of Aleppo on Tuesday, January 1.
Syrians reach for bread at a bakery in Aleppo on Monday, December 31.
Free Syrian Army fighters stand near damaged cars in Aleppo on Thursday, December 27.
A man walks near a missile on Tuesday, December 25, at an army barracks outside Damascus, Syria, that has been taken over by the Free Syrian Army.
Free Syrian Army fighters prepare a homemade missile before they launch it toward the military airport in Aleppo, Syria, on Sunday, December 23.
Free Syrian Army members display shrapnel from what they say are the remains of a rocket fired from the Syrian army in northern Aleppo on Thursday, December 20.
An unexploded bomb is seen lodged in a street in Ghouta, east of Damascus, Syria, Wednesday, December 19.
A Free Syrian Army fighter aims his weapon through a hole in the wall of the structure where he is positioned in the Qastal Harami area of Aleppo on December 19.
A child sits in the back of a vehicle at the border crossing leading to Masnaa, Lebanon, as people wait to stamp their documents before leaving Syria on December 19. Click through to view images from Syria from December, or see photos of the conflict from November.
Palestinian children who fled the Syrian refugee camp of Yarmuk wait at the Masnaa Border Crossing leading into Lebanon on December 19.
Syrians line up outside a bakery offering cheap bread in Aleppo, Syria on Sunday, December 16.
A Syrian boy walks past a rebel fighter in the northern town of Darkush, Syria, on Friday, December 14.
Two men on a motorcycle lead a horse through the northern town of Darkush, Syria, on December 14, 2012.
Rebel fighters push out a boat carrying two Syrian women fleeing to Turkey through the Orontes River near the northern Syrian town of Darkush on December 14.
Passengers gather at a terminal at the airport in Aleppo, Syria, on Wednesday, December 12.
A member of the Syrian opposition's Al-Buraq Brigade stands guard on a main road in the northern Syrian town of Ain Dakna near the Turkish border on Monday, December 10. Click through to view images of the fighting from December, or see photos of the conflict from November.
A Free Syrian Army fighter takes position as he aims his weapon in Aleppo's al-Amereya district on Tuesday, December 11.
Men warm themselves by a fire on a street corner in Aleppo, Syria, on Sunday, December 9.
A rebel soldier watches Al-Jazeera news in a shop near the front lines in Aleppo on December 9.
A rebel soldier prays in a shop in Aleppo on December 9.
Syrians mourn a fallen fighter at a rebel base in the al-Fardos area of Aleppo on Saturday, December 8.
A Syria rebel commander sits behind a desk in his bombed-out position in Aleppo on December 8.
A Syrian rebel fighter emerges from a hole in a wall in Aleppo on December 8.
Rebel fighters take part in a demonstration against the Syrian regime after Friday prayers in Aleppo on December 7.
A wounded rebel fighter is transported to a hospital in the back of a truck in Aleppo, Syria, on Thursday, December 6. At least 23 people died in Syria on Thursday, most of them in Damascus and Aleppo, according to the opposition Local Coordination Committees of Syria.
Rebel soldiers stand guard inside a building in Aleppo on December 6.
Angelina Jolie, special envoy for the U.N. refugee agency, meets with Syrian refugees at the Zaatari refugee camp outside Mafraq, Jordan, on December 6.
In this handout from the Shaam News Network, Free Syrian Army fighters stand guard against forces loyal to Syrian President Bashar al-Assad in the Al-khalidiya neighborhood of Homs on Tuesday, December 4.
In this handout from the Shaam News Network, Free Syrian Army fighters take cover in destroyed buildings during clashes with regime forces on December 4.
Syrians cross the border from Ras al-Ain, Syria, to the Turkish border town of Ceylanpinar on Tuesday, December 4.
Boys walk through a damaged area In Aleppo, Syria, seen through a destroyed car on December 4.
A man inspects rubble in a neighborhood of Aleppo on Sunday, December 2.
The bodies of three children reportedly killed in a mortar shell attack are laid out for relatives to identify at a makeshift hospital in Aleppo on December 2.
Smoke rises from fighting in the Hanano and Bustan al-Basha districts of Aleppo on Saturday, December 1.
Syrian-Kurdish women and members of the Popular Protection Units, an armed opposition group to the Syrian government, stand guard during a comrade's funeral in a northern Syrian border village on December 1.
- NEW: The rebel claim of capturing the base is called 'significant' by the U.S.
- The United Nations says there are more than 612,000 Syrian refugees
- Dozens are killed Friday in Syria, the opposition says
- As the civil war rages, world leaders push to ensure chemical weapons are secure
(CNN) -- Syrian rebel fighters said Friday they have captured a strategic northern military base used by the government to bomb opposition strongholds.
Rebel fighters and militants from various Islamic groups, including the jihadist al-Nusra Front, took part in the offensive, an opposition spokesman said.
They've seized control of buildings, ammunition and military equipment at the base in Idlib province, the opposition said, signaling a major blow to President Bashar al-Assad's forces.
"They are taking credit now for having taken the air base," U.S. State Department spokeswoman Victoria Nuland told reporters Friday. "And, as you know, we consider this significant on two fronts.
"First of all, to ground some of the air assets of the Assad regime that they've been using against civilians. And, secondly, to break their ability to resupply in the north."
Read more: Pentagon weighs how to secure Syria's chemical weapons
The strategic base has been used by government forces to send explosives to areas in the north, according to the opposition Syrian Observatory for Human Rights.
In addition to housing about government 400 soldiers, the group said, warplanes that attack the region were taking off from there.
"The Taftanaz air base has been completely liberated," said Hamza Abu Hussam, a spokesman for the Binnish Coordination Committee, a local opposition group.
"I went down to see with my own eyes and was able to get in."
Read more: Terrorist group fills power vacuum among Syria rebels
In a video posted on YouTube, opposition forces from various groups cheer and chant "God is great," purportedly after they took over the military airport.
CNN cannot independently verify the authenticity of the video.
Brahimi: No military solution
The U.N. and Arab League special envoy to Syria stressed Friday that there is "no military solution" to the brutal civil war being fought in the Arab nation.
Lakhdar Brahimi made the remark after meeting with Russian Deputy Foreign Minister Mikhail Bogdanov and U.S. Deputy Secretary of State William Burns on Friday at the United Nations offices in Geneva, Switzerland.
"We are all very, very deeply aware of the immense suffering of the Syrian people which has gone for far too long. And we all stressed the need for a speedy end to bloodshed, the destruction, and all forms violence in Syria," he said. "We stressed again, in our view, there is no military solution to this conflict."
Syria accused Brahimi of bias Thursday, casting a shadow on efforts to end a war that, according to the United Nations, has killed more than 60,000 people in nearly two years.
Brahimi has "deviated from the essence of his mission and clearly unveiled his bias to circles known for conspiring against Syria and the interests of the Syrian people," Syrian state media reported.
The statement from Damascus was a response to a BBC interview in which Brahimi in effect called on al-Assad to resign. He said the president would have no place in the transition to a post-conflict Syria.
"I think what people are saying is, a family ruling for 40 years is a little bit too long," Brahimi said, according to the interview Thursday.
Al-Assad took over from his late father, who seized power in 1970 and ruled for three decades.
Brahimi said both the United States and Russia want to help end the war and forge a future. The United States long has called for al-Assad to resign. Russia, which historically has had close ties with Syria, has blocked tough action against the government in the U.N. Security Council.
"I'm absolutely certain the Russians are as preoccupied as I am, as Americans are, by the bad situation that exists in Syria and its continuing deterioration, and I'm absolutely certain they would like to contribute to its solution," he said.
He cited the "absolute necessity" for pushing for a peaceful solution.
"It is the wider international community," he said, particularly Security Council members, who "can really create the opening that is necessary to start effectively solving the problem."
Securing chemical weapons
The escalating conflict and the president's efforts to retain his grip on power have sparked a push to ensure that chemical weapons are secure.
U.S. officials say they are working with nations in the Middle East to secure Syria's chemical and biological weapons sites.
"We're not talking about ground troops, but it depends on what ... happens in a transition," Defense Secretary Leon Panetta said Thursday.
Asked whether he had ruled out putting U.S. troops in Syria to secure such weapons, Panetta said: "You always have to keep the possibility that, if there is a peaceful transition and international organizations get involved, that they might ask for assistance in that situation. But in a hostile situation, we're not planning to ask for that."
Russian navy holding exercises off Syria's coast
Ships of the Russian Black Sea Fleet are heading to the eastern Mediterranean for exercises, the Russian Defense Ministry said.
A tactical group of Black Sea Fleet warships, headed by the cruiser Moskva, will undertake exercises in the eastern sector of the Mediterranean Sea. The tanker Ivan Bubnov has fueled the ships, and emergency drills have been carried out for the upcoming exercises. The tanker filled up on fuel and water Thursday at the Cyprus port of Larnaka.
A Baltic Fleet group consisting of the patrol vessel Yaroslav Mudry and tanker Lena will head for the eastern Mediterranean, where the two ships will practice stores transfers at sea. The patrol vessel will carry out anti-submarine warfare drills.
Russia has a maintenance naval base at Tartus on the coast.
No let-up in refugee flight
The United Nations said Friday that more than 612,000 people have been registered as Syrian refugees or are "being assisted as such."
There were 194,769 in Lebanon, 176,569 in Jordan, 153,163 in Turkey, 69,282 in Iraq, 13,292 in Egypt and 5,059 elsewhere in North Africa, the U.N. refugee agency said.
"Even with the winter preparation work that has been done in recent months, many refugees in both camp and noncamp situations are facing particularly cold and damp conditions. At the same time, there has been no let-up in the numbers of people fleeing Syria into neighboring countries," the U.N. High Commissioner for Refugees said.
More deaths
The Syrian crisis started in March 2011, when peaceful protesters demanding democracy and reforms were met by a fierce government crackdown, which spiraled into an armed opposition movement and a civil war.
At least 60 people were killed Friday, the opposition Local Coordination Committees of Syria said. Among them were 40 people killed in shelling by artillery and jet fighters in Hasaka province, in the northeastern part of the country.
Read more: By the numbers: Syria deaths
CNN's Joe Sterling and Saad Abedine reported from Atlanta. CNN's Alla Eshchenko in Moscow and Faith Karimi in Atlanta contributed to this report.