A Syrian shopkeeper waits for customers next to paintings of of President Bashar Assad, and Hezbollah leader Sheikh Hassan Nasrallah, center, at the Souk Tawil market in Damascus, Syria. BEIRUT – A cease-fire brokered by Russia and Turkey went into effect in war-ravaged Syria tonight, a potential breakthrough in the six years of fighting that have left more than a quarter-million people dead and triggered a refugee crisis across Europe.