However, the rebel alliance is a fractured collection of militiamen and freelance revolutionaries with no central leadership.
Opposition activists say the bombings, like the attacks in Damascus, are suspicious in part because the explosions successfully targeted heavily guarded security posts. Both vehicles in Aleppo managed to get close enough to cause extensive damage.
One activist who said he had been released this week after being held for two weeks at a military facility that was bombed Friday, said the gates were opened only after careful security checks. "There is no human who can come close because there are cement checkpoints," the activist said.
Despite Aleppo's pro-Assad reputation, the opposition says the protest movement has been growing there, a worry for the government.
After Friday's bombings, opposition activists said, protesters took to the streets in two neighborhoods, Fardous and Marje. In one case, authorities opened fire, killing at least 13, according to the Local Coordination Committees, an opposition coalition. It was one of the bloodiest protest clashes to date in Aleppo.