Government shelling and airstrikes with makeshift barrel bombs have killed about 400 people in Syria’s largest city so far this month, activists said Thursday, as U.S. and Russian envoys met in Geneva to try to revive deadlocked peace talks.

The bombings in Aleppo are part of a campaign by President Bashar Assad’s forces to wrest control of neighborhoods that were seized by rebels in the northern city since mid-2012.

They come as a cease-fire in the central city of Homs has been extended for three days as of Thursday in order to allow more people to leave besieged rebel-held parts of the city, the Homs governor said. […]