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Syrian forces launch air attacks as rebels push on largest city

Dozens are reported dead in Syria where opposition forces are fighting to maintain control of Syria's commercial capital and biggest city. NBC's Richard Engel reports.

Fierce clashes intensified in Syria's commercial capital of Aleppo on Tuesday as the government unleashed air attacks on rebellious neighborhoods, while activists claimed opposition fighters had control over several neighborhoods in the city.

Government helicopter gunships attacked Aleppo, the Local Coordination Committees, a network of on-the-ground activists, told NBC News. The Associated Press reported that warplanes circled in the air around the city, while the British Broadcasting Corp., citing one of its reporters near the area, said that fighter jets had bombed eastern parts of Aleppo.

With sequential rebel attacks on the country's two largest cities and a bombing that wiped out some of his top security advisors, President Bashar Assad reshuffled his top security posts, dismissing one general and appointing a national security council chief to replace the one killed in the recent attack. 

Syria's rebels, outmanned and outgunned by the regime's professional army, have mounted a surprising pair of offensives over the last 10 days against the country's two major cities — Damascus and Aleppo. Even as the government appears to have snuffed out most of the rebel pockets in the capital, the rebels appear to be fight fiercely in the commercial hub of Aleppo in the north.

The government has instituted tight restrictions on outside news outlets working in Syria, making it difficult to verify many reports from inside the country.

Fighting spreads in Aleppo
The battle in Aleppo has spread from neighborhoods in the northeast and southwest of the city to previously untouched areas like Firdous in the south and Arkoub closer to the center, local activists and the Britain-based Syrian Observatory for Human Rights said.

At least 20 people have been killed in the fighting in Aleppo, the Local Coordination Committees told NBC.

Opposition activist Mohammed Saeed has estimated that the rebels are holding large chunks of the city and the government has responded with attack helicopters — key to their retaking of Damascus over the last few days.

Circling fighter jets have also been breaking the sound barrier overhead in an apparent attempt to cow the fighters, the AP reported.

Syria acknowledges it has chemical weapons, will use them if attacked

"It's like a real war zone over here, there are street battles over large parts of the city," Saeed said, with the sound of gunfire and explosions audible over the phone. "Aleppo has joined Homs and Hama and other revolutionary cities."

Syria's government is acknowledging for the first time it has the ability to use chemical and biological weapons, though the government says those weapons wouldn't be used on the country's citizens. The Morning Joe panel – including New York Magazine's John Heilemann and the Council on Foreign Relations' Dan Senor and Richard Haass – discusses.

On Sunday, a newly formed alliance of rebel groups called the Brigade for Unification announced an operation to take Aleppo, the country's largest city with about three million people. While the rebels have not shown themselves able to hold neighborhoods for any significant period of time, the continued fighting highlights the government's inability to pin down the lightly armed opposition forces.

Prisoners in Aleppo's jail also rioted overnight and activists said at least eight have been killed by government forces. Another prison riot in the city of Homs has been quelled with tear gas and live ammunition.

The International Committee of the Red Cross issued a statement Tuesday calling the situation in and around Damascus "tense and volatile."

"People have been calling us on a daily basis, saying they need a helping hand," Marianne Gasser, the ICRC's head of delegation in Syria, said in the statement. "Some are in need of the basics -- items one usually takes for granted, such as water and food, and a mattress to sleep on. But first and foremost, they are in need of safety."

NBC's Ayman Mohyeldin answers your questions about Syria

With the conflict raging in Syria's two biggest cities, as well as many provincial ones, Western and many Arab nations are pushing for Assad's removal, although Russia, China, Iran and Iraq are among others opposed to any forced handover of power.

The ferocity of the Syria conflict, in which 1,261 people have been killed since fighting intensified in Damascus on July 15, according to one opposition watchdog, has concentrated attention on the possible repercussions of Assad's overthrow.

Warning over chemical weapons
As the struggle for Syria intensified, Western leaders seized on an admission by Damascus that it has chemical and biological arms and could use them if foreign powers intervened.

Analysts: Russia will be big loser if Assad falls

President Barack Obama said the world would hold Assad and his entourage accountable "should they make the tragic mistake of using those (chemical) weapons."

Israel, which has publicly discussed military action to prevent Syrian chemical weapons or missiles from reaching Assad's Lebanese Shiite militant allies Hezbollah, said there was no sign any such diversion had occurred.

"At the moment, the entire non-conventional weapons system is under the full control of the regime," a senior Israeli defense official, Amos Gilad, told Israel Radio.

Syrian Foreign Ministry spokesman Jihad Makdissi said the army would not use chemical weapons to crush rebels but could use them against forces from outside the country.

The Global Security website, which collects published intelligence reports and other data, says there are four suspected chemical weapons sites in Syria: north of Damascus, near Homs, in Hama and near the Mediterranean port of Latakia. Weapons it produces include the nerve agents VX, sarin and tabun, it said, without citing its sources.

NBC News' Ayman Mohyeldin, The Associated Press and Reuters contributed to this report.

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