Israeli warplanes flew across Lebanon on Monday, breaking the sound barrier on what appeared to be a reconnaissance mission, a Lebanese security official said. Four Israeli jets flew over the southern cities of Sidon and Tyre and the Bekaa Valley in eastern Lebanon, an official said, speaking on customary condition of anonymity. The planes caused some panic among the inhabitants of Akkar, a town near the east Lebanese border with Syria, the official added. There was no immediate comment from Israel. Lebanese army gunners did not fire at the jets, the Lebanese official said.