Rebels in Syria have announced a big offensive aimed at breaking the government siege of east Aleppo.
A UK-based monitoring group says rebels fired "hundreds" of missiles on western Aleppo, killing at least 15 civilians.
In response, Russia's defence ministry asked permission from President Vladimir Putin to resume air strikes against the rebels after a 10-day pause, but he denied the request.
About 275,000 people have been besieged in the east of the city for months.
Russian and Syrian government planes began bombarding the city in September. More than 2,700 people are said to have been killed and injured since then.