In a statement released in Beirut, Staffan de Mistura “again calls upon the Israeli authorities to cease all air violations and to fully respect the Blue Line,” as the withdrawal line is known. Such actions, he said, “are unhelpful in avoiding the deterioration of an already tense situation.”Mr. de Mistura made his comments on a day when nine Israeli jets committed a total of six violations. Sonic booms were also heard in Beirut and southern Lebanon on Friday. The previous day, air violations were committed by two Israeli military aircraft.