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Free Syrian Army fighters overrun police station in Aleppo

Pierre Torres / AFP - Getty Images

Free Syrian Army opposition fighters battle government security forces during the siege of the Shaar district police station in the northern Syrian city of Aleppo on July 25, 2012. The police station was later overrun by rebel forces.

Pierre Torres / AFP - Getty Images

Opposition fighters prepare home-made firebombs in Aleppo on July 25, 2012.

Pierre Torres / AFP - Getty Images

Free Syrian Army opposition fighters battle government security forces during the siege of the Shaar district police station on July 25, 2012. Arabic graffiti on the police station entrance read "Assad's Syria".

Pierre Torres / AFP - Getty Images

A masked opposition fighter poses inside the Shaar district police station after it was overrun by Free Syrian Army forces on July 25, 2012.

Pierre Torres / AFP - Getty Images

Syrian policemen stand with their hands behind their backs after being detained by Free Syrian Army opposition fighters who overran the Shaar district police station on July 25, 2012.

Pierre Torres / AFP - Getty Images

Civilians leave their homes to look for safer areas during a lull in fighting between opposition forces and army troops in Aleppo on July 25, 2012.

By NBC News and wire reports — President Bashar Assad's forces withdrew from towns and villages throughout Syria on Thursday and turned toward the key city of Aleppo, pounding rebels with artillery and attack helicopters in the country's commercial hub. 

"It could be a humanitarian disaster for the people of Aleppo," NBC News' Richard Engel reported from northern Syria. "It also means the Syrian troops are forced to make trade-offs. They don't have enough loyal troops to make the offensive against Aleppo and hold these rural areas." Read the full story.

NBC's Richard Engel reports from Syria, where government loyalists are launching a major counter-offensive to maintain control of Aleppo, the nation's largest city, which is considered to be critical to the survival of the Syrian government.

After months of protests and violent crackdowns, a look back at the violence that has overtaken the country.

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