Syria peace talks falter as army presses Aleppo

By Tom Perry, Suleiman Al-Khalidi and John Irish BEIRUT/AMMAN/GENEVA (Reuters) - A Syrian military offensive threatened critical rebel supply lines into the northern city of Aleppo on Tuesday and Damascus echoed its opponents in contradicting a U.N. envoy's assertion peace talks had begun. U.N. envoy Staffan De Mistura announced the formal start on Monday of the first attempt in two years to negotiate an end to a war that has killed 250,000 people, caused a refugee crisis in the region and Europ