Israeli jets have carried out raids on Beirut and across southern Lebanon. No weapons were fired, but the jets flew low over buildings and released a sonic boom.
Eight planes were involved. It is the most serious violation of the ceasefire which came into place at the start of August.
Last week French UN peacekeepers threatened to attack Israeli planes if they continued to invade Lebanon.
Israel has flown over Lebanese airspace for decades, its last flight was just days ago.