U.N. to spotlight Syrian civil war as bloodshed mounts daily Raising pressure on al-Assad is a goal at the U.N., Germany's top diplomat says Opposition: Warplanes shell Aleppo, flattening buildings and killing three children At least 24 people are killed across Syria on Monday, opposition activists say Syrian dissidents figures meet in Damascus, under the regime's watch (CNN) -- As diplomats from around the world converge on New York for the U.N. General Assembly this week, the Syrian civil war -- and what to do about the country's embattled regime -- will be high on the agenda. Some of the main goals are "to increase pressure and to increase the isolation of the regime of al-Assad," German Foreign Minister Guido Westerwelle said. Germany holds the rotating presidency of the U.N. Security Council this month. But if history repeats itself, talks about Syria at the United Nations won't necessarily amount to effective action at the world body. Many countries decry what they say is the Syrian government's cruel, violent treatment of civilians, and some have issued sanctions against the Syrian government. More: Why Libyan fighter joined rebels Yet action at the U.N. Security Council has been muted. Countries such as the United States, France and Great Britain have tried to formally denounce Syrian President Bashar al-Assad's regime, but such attempts have been vetoed by Russia and China. Both Russia and China say they oppose foreign intervention in Syria and want an internal political solution. But some analysts say they believe the two countries are worried about trade ties. As world leaders remain at an impasse on what to do about Syria, dozens or hundreds of people are reportedly killed each day in the country. Here are the latest developments in Syria's 18-month crisis: On the ground: Terror in Syria's largest city The commercial hub of Aleppo became a battlefield once again Monday, with children falling victim to incessant government attacks, opposition activists said. At least eight people -- including three children -- were killed after warplanes pummeled a city neighborhood, the Local Coordination Committees of Syria said. More: Syrian Christians fear future Several residential buildings were flattened, the opposition group said. Across the country, at least 24 people were killed in fresh violence Monday, according to the LCC. They join more than 26,000 people who have died in Syria since March 2011, opposition activists said. In the capital: Dissidents call for al-Assad's ouster With the knowledge of Syria's rulers, opposition figures met Sunday in the capital city of Damascus and urged "toppling the regime." Denouncements of the Syrian regime are nothing new among opposition groups, though it is rare for them to be made in Damascus -- effectively under the government's watch. But one of the most prominent and vocal opposition groups, the Syrian National Council, was not represented at the meeting Syrian state-run media acknowledged the meeting of dissidents, but failed to mention the call for al-Assad's ouster. Organizers of the conference later issued a statement detailing positions agreed to by participating groups, including toppling the regime and building support for a democratic state. More: Damascus residents 'stuck in middle' The dissidents also agreed to pursue "non-violent resistance ... to accomplish the goals of the revolution" and praised those Syrian troops who had refused to "kill their fellow countrymen" and defected to join the rebel Free Syrian Army. A day before the summit began, the event's organizers -- the National Coordination Body for Democratic Change -- said that three of its members were detained by Syrian Air Force Intelligence personnel after driving from Damascus International Airport on Thursday. CNN's Holly Yan, Saad Abedine and Sonia Kennebeck contributed to this report.