CAIRO -- As a group of rebels gathered in an apartment in Aleppo, Syria's largest city, debating the value of the U.S. decision to provide them with weapons, government forces nearby began pounding an opposition-held neighborhood.
The opposing events led the group to focus on a question asked Friday by many in Syria's beleaguered opposition: Would the promised aid come in time, or would be it be too little, too late?
An older rebel who leads a few dozen fighters on one of the front lines in Aleppo was skeptical. "I'll believe that America is helping us when I see American arms in my group's hands, not statements and food baskets," said the 40-year-old fighter, who calls himself Abu Zaki.
At the same time, he said, he did not understand U.S. fears that arms would go to Al Nusra Front, a rebel group linked to al-Qaida, since it has never attacked Western targets.
The announcement Thursday that the United States had concluded that the forces of Syrian President Bashar Assad had used chemical weapons, and that President Barack Obama was now prepared to send light arms and ammunition to the rebels, set off a similar debate around the world. Allies and adversaries of the Syrian president argued whether the decision would help speed the conflict's end or only escalate the bloodshed.
"What are we going to do about the fact that in our world today, there is a dictatorial and brutal leader who is using chemical weapons under our noses against his own people?" British Prime Minister David Cameron asked in an interview with The Guardian newspaper.
Mr. Assad's allies in Russia and Iran condemned Mr. Obama's decision, and the leader of the Lebanese militant group Hezbollah, Hassan Nasrallah, vowed to continue fighting on behalf of the Syrian government "wherever needed."
In a phone call Friday, Russian Foreign Minister Sergey V. Lavrov told U.S. Secretary of State John Kerry that U.S. support for the opposition risked escalation in the region.
Syria's conflict began in March 2011 with protests calling for political reform. Since then, it has evolved into a civil war. The war, which the United Nations said Thursday had killed more than 90,000 people, has accented sectarian divisions inside Syria and across the Middle East.
The rebels mostly hail from Syria's Sunni Muslim majority and are primarily backed by the Sunni monarchies of Qatar and Saudi Arabia. Mr. Assad's government has long given privilege to members of his Alawite minority and is backed by the region's Shiites, including Iran and Lebanon's Hezbollah. Their strategic alliance allows Iran to use Syria as a crucial land link for delivery of arms to Hezbollah in Lebanon.
Once the government, with Hezbollah's help, managed to rout the rebels from the city of Qusair, there were fears that the forces would move on Aleppo. It was not clear Friday whether the heavy fighting represented the start of an all-out attack or just another skirmish, but the timing served to magnify the significance of Washington's announcement. Fighting that anti-government activists described as the heaviest in months raged Friday around the eastern rebel-held neighborhood of Sakhour, according to the Syrian Observatory for Human Rights, a Britain-based group that relies on a network of contacts in Syria.
A rebel commander reached in Aleppo via Skype called the U.S. decision "good news," but said what the rebels really needed were anti-tank and anti-aircraft missiles. Reflecting the questions that remain about which rebels the United States will arm, the commander, Jamal Maarouf, said he did not know whether his group would qualify. "The American said they will arm moderate battalions," he said. "I don't know if my battalion is moderate."