A deal to create a demilitarized zone in Syria’s last opposition stronghold and forestall a regime offensive faces an immediate challenge from terrorist groups there who have signaled their reluctance to abide by the agreement.
Hayat Tahrir al-Sham, one of the most powerful armed groups in Syria’s Idlib Province, criticized the accord made this week between Russia and Turkey to avert a government offensive. The deal for a demilitarized zone would remove heavy weapons and expel officially designated terrorist groups from...