BEIRUT- A Syrian rebel leader said on Monday there could be no negotiations to end the civil war until President Bashar al-Assad stepped down and leaders of the army and security forces were put on trial."We will not go (into talks) unless these demands are realized," Brigadier Selim Idris, head of a military command, told Al Arabiya Television.He was speaking after Syrian Foreign Minister Walid al-Moualem said in Moscow the government was ready to hold talks with Assad's armed opponents.