Regime assault troops and armored columns positioned around Syria\'s densely populated commercial capital were poised Friday to attack, residents said. Syrian military commanders appeared to be waiting for reinforcements before issuing invasion orders, The New York Times reported Friday, pointing to military experts who have speculated President Bashar Assad\'s army -- already fighting rebellions in Homs, Hama and more recently in Damascus -- lacked the military resources to simultaneously take on an armed rebellion in Aleppo -- one of the oldest continuously inhabited cities in the world. An estimated 2,000 rebel soldiers positioned in Aleppo were reinforced by about 2,000 more, including foreign fighters, activists said. Rebel forces claim to control 60 percent of Aleppo as well as the main road to the airport, the Spanish newspaper El Pais reported Friday. Panicked residents said Aleppo was rife with rumors the army\'s elite Fourth Armored Division, commanded by Assad\'s younger brother Maher Assad, was mobilizing for a brutal counteroffensive -- including a possible \"scorched earth\" operation, destroying anything that might be useful to the enemy while advancing through the city. Maher Assad is part of the regime\'s inner circle and is thought by some diplomats to be the second-most powerful man in Syria. His fearsome division, widely regarded as the best trained and best equipped of the Syrian army, is drawn mostly from members of the same Alawite group as the Assad family and is composed almost exclusively of career soldiers and officers, in contrast to the regular Syrian army, made up largely of conscripts. \"We are terrified,\" a resident named Ahmed told the Times. France called for U.N. action to stop a potential \"bloodbath.\" U.N. Secretary-General Ban Ki-moon warned world powers not to repeat mistakes they made in the 1992-1995 Bosnian War that followed the breakup of Yugoslavia. \"I don\'t want to see any of my successors after 20 years visiting Syria and apologizing for what we could have done now to protect civilians in Syria, which we are not doing,\" Ban said in Srebenica, scene of a July 1995 massacre by the Bosnian Serb Army of more than 8,000 Bosnian Muslims, mostly men and boys. Then-U.N. Secretary-General Kofi Annan, who is now the U.S.-Arab League special envoy to Syria, described the Srebenica mass murder as the worst war crime on European soil since World War II. U.S. State Department spokeswoman Victoria Nuland told reporters in Washington Thursday the Obama administration was concerned \"we will see a massacre in Aleppo, and that\'s what the regime appears to be lining up for.\" She said the administration was not reconsidering its stance against military intervention, saying, \"We do not think pouring more fuel onto the fire is going to save lives.\" Shelling occurred in and around Aleppo overnight, said residents who hadn\'t fled the nearly Chicago-size city of more than 2 million. Fierce clashes took place Thursday between the opposition Free Syrian Army and regime forces on the northern and western roads approaching Aleppo, activists said. The official Syrian Arab News Agency reported clashes between the army and armed groups had \"resulted in the killing and wounding of many terrorists.\"