Fierce air strikes on Aleppo after Syrian army declares offensive

By Ellen Francis and Tom Perry BEIRUT (Reuters) - Warplanes launched some of the heaviest air strikes yet on rebel-held areas of Aleppo on Friday after the Russian-backed Syrian army declared an offensive to fully capture Syria's biggest city, killing off any hope of reviving a ceasefire. Residents said the streets were deserted as the 250,000 people still trapped in the besieged opposition-held sector of Aleppo sought shelter from jets. The rebels and the Syrian Observatory for Human Rights mon