DAMASCUS, Syria — Fighting shattered a fragile three-day truce Aug. 15 as military operations resumed on three fronts: the Syrian regime and its Iranian-backed Lebanese ally Hezbollah against opposition fighters in the mountain city of Zabadani and the opposition's Ahrar al-Sham movement in the two pro-regime, Shiite-majority cities of al-Fawaa and Kefraya in theprovince of Idlib.