Syrian rebels brace for assault on Aleppo

Rebels have been fighting for six days in the commercial capital Aleppo, and yesterday they braced for a government onslaught amid reports that the regime is massing reinforcements to retake the city of 3 million.

They reported more intense firepower being used against them, including artillery strikes. "Regime forces have been randomly shelling neighborhoods, and the civilians are terrified," local activist Mohammed Saeed said.

U.S. State Department spokeswoman Victoria Nuland said Washington has "grave concerns" about tanks and fighter jets being used in a densely populated city. "The concern is that we will see a massacre in Aleppo, and that's what the regime appears to be lining up for."

The clashes have spread to neighborhoods close to the center of the city, which has a medieval center that is a UNESCO world heritage site.

According to the Britain-based Syrian Observatory for Human Rights, about 130 people have been killed in Aleppo since the clashes there began Saturday.

UN Secretary General Ban Ki-moon said he fears for Syria's future. Yesterday, he paid his respects to the 8,000 victims of the 1995 Srebrenica massacre, and said he does not want a successor to have to do the same in Syria.

"The international community must be united not to see any further bloodshed in Syria because I do not want to see any of my successors, after 20 years, visiting Syria, apologizing for what we could have done now to protect the civilians in Syria -- which we are not doing now," he said at a memorial-cemetery complex near Srebrenica, Bosnia-Herzegovina.

The conflict in Syria, which activists say has killed more than 19,000 people since March 2011, has drawn deep international condemnation. But world powers have few options to help beyond diplomacy -- in part because of fears that any military intervention could exacerbate an already explosive battle. Syria's close ties to Iran and the Islamic militant Hezbollah in Lebanon mean that the conflict has the potential to draw in the country's neighbors.

In Washington, the Obama administration was weighing its options for more direct involvement if the rebels opposing the Assad regime can wrest enough control to create a safe haven for themselves, U.S. officials said.