QAMISHLI, SYRIA — The Kurdish-led Syrian Democratic Forces said Tuesday they have launched a counteroffensive against the Turkish-backed Syrian National Army to take back areas near Syria’s northern border with Turkey. The SDF is Washington’s critical ally in Syria, targeting sleeper cells of the extremist Islamic State group scattered across the country’s east. Since the fall of the totalitarian rule of Bashar al-Assad earlier this month, clashes have intensified between the U.S.-backed group and the SNA, which captured the key city of Manbij and the areas surrounding it. The intense weekslong clashes come at a time when Syria, battered by
