BEIRUT—Syria’s last opposition stronghold is bracing for a regime military offensive, after airstrikes and shelling killed dozens there in recent days and the United Nations warned of a possible humanitarian disaster.
Syrian regime airstrikes and artillery attacks have pounded parts of the northwestern province of Idlib and surrounding areas in the past week, killing and injuring scores of civilians, according to rebels there and the White Helmets, a volunteer rescue organization. Shelling continued Friday on at least one...