BEIRUT — Syrian government forces and their allies Monday captured strategic high ground in embattled Aleppo as Russia — a key ally of Syrian President Bashar Assad — said it was not planning more “humanitarian pauses” in the fighting in the city's eastern, rebel-held districts.

The fighting in Aleppo came as airstrikes hit towns in the province of Idlib, killing at least 13 people, according to the Britain-based Syrian Observatory for Human Rights and the Local Coordination Committees. Fighting resumed in Aleppo over the weekend, following a dayslong lull.