Syrian insurgent advances put Assad under pressure

A rebel fighter stands with his weapon at a building after what activists said were clashes with Islamic State fighters in Soran Azaz, Aleppo countryside June 1, 2015. Picture taken June 1, 2015. REUTERS/Mahmoud Hebbo

BEIRUT (Reuters) - Steady advances by insurgents on key fronts in Syria mean President Bashar al-Assad is under more military pressure than at any point in the four-year-old war.

Losses in the north, east and south to groups including al Qaeda's Syrian arm and Islamic State may test Assad's hold over western parts of the country that are the most crucial to his survival.