A children’s advocacy group warned Friday that nearly half of nearly 400,000 displaced in the Syrian government’s two-month-long offensive on the country’s last rebel-held region are children, calling it a wave of displacement unlike anything seen before in the war in Syria. The offensive by the Syrian government forces, backed by ally Russia, has focused mainly on Idlib province, and also lately on neighboring Aleppo, in an attempt to seize control of a strategic highway that links the capital, Damascus, and the north. The push accelerated in the last two weeks and the government forces on Wednesday seized control of the key own of Maaret al-Nouman that sits along the highway.