Syrian troops backed by Russian air power have been battling since December to eliminate the last rebel strongholds in the region in a war that has killed an estimated 400,000 Syrians, displaced millions more and left much of the country in ruins.
The latest offensive in the northwestern regions of Aleppo and Idlib has uprooted nearly 1 million people - most of them women and children - who fled clashes to seek sanctuary further north, near the Turkish border.
