Lebanon says its army has opened fire on four Israeli warplanes that flew into Lebanese airspace. The Lebanese army said in a statement that its units used anti-aircraft fire Sunday to force the Israeli warplanes out of Lebanese airspace. The army said the planes were in southern Lebanon and the Beqaa Valley, in central Lebanon.Israeli warplanes frequently fly over Lebanese airspace in what Israel says are reconnaissance missions. The overflights and violations of UN Security Council resolutions have been a constant source of tension between the two countries. Sunday's events come amid heightened tensions in the Middle East following some of the sharpest exchanges in years between Israel and its Arab neighbors.