NEW : United Nations secretary-general expresses `` grave concern '' about airstrike . Iran , Russia and Hezbollah condemn the attack . Syrian reports that strike hit research center are wrong , U.S. official says . Comment:
NEW : United Nations secretary-general expresses `` grave concern '' about airstrike . Iran , Russia and Hezbollah condemn the attack . Syrian reports that strike hit research center are wrong , U.S. official says . Sources say the airstrike hit a convoy hauling missile parts .