The Syrian civil war, seemingly frozen in an uneasy deadlock for years, has been reignited with rebel forces wresting Aleppo, the country’s second biggest city, from President Bashar al-Assad ’s grasp.

Syrian and Russian jets are stepping up strikes on opposition forces in northern Syria in retaliation for the sudden offensive that has cost the regime control of the country’s second largest city, Aleppo.

Syrian rebel fighters began preparations to seize Aleppo a year ago but the operation was delayed by war in Gaza and ultimately launched last week when a ceasefire took hold in Lebanon, the head of Syria's main opposition abroad told Reuters.

Syrian state SANA news agency on Wednesday said insurgents retreated some 20 kilometers (12 miles) from government-held Hama, Syria’s fourth-largest city, as government troops backed by

The leader of Syria’s most powerful insurgent group has toured the seized city of Aleppo in a surprise visit, the first since the insurgents captured large parts of the city over the weekend as fierce

Assad’s favor after a Russian blitzkrieg on Aleppo helped him regain control over the country’s second biggest city.

Rebels captured Syria's second-largest city, Aleppo, over the weekend and advanced toward Hama in a surprise incursion that reignited Syria's 13-year-old civil war and embarrassed President Bashar al-Assad's forces.

Syria carried out airstrikes targeting the rebel forces that seized the country's second largest city of Aleppo in a surprise advance last week that caught the government off guard.

Syria said Wednesday its counteroffensive has pushed back insurgents attempting to advance to the strategic central city of Hama, while the insurgency says it captured more Syrian troops and Iran-backed militants in fierce battles.

Fox News chief national security correspondent Jennifer Griffin has the details from The Pentagon on 'Varney & Co.'