The Lebanese Armed Forces and UNIFIL troops have increased their observation activities on the Israel-Lebanon border, the official Lebanese National News Agency reported on Friday.The increased activity came a day after the Israel Air Force shot down a drone that flew south from Lebanon over the Mediterranean Sea about eight kilometers off the coast of Haifa. Hezbollah, who had a drone shot down by the IAF in the Negev in October, denied having sent an unmanned aerial vehicle to Israel on Thursday. According to Friday's Lebanese report, IDF troops along the Lebanese border were on high alert.The report added that IAF jets and helicopters had been witnessed flying over towns in southern Lebanon on Friday.On Thursday, IDF air defenses picked up the drone shortly after 1 p.m., and F-16 fighter aircraft and combat helicopters scrambled to intercept it.Simultaneously drama unfolded in the skies in the North, as an air force helicopter carrying Prime Minister Binyamin Netanyahu on a visit to a Druse village in the Western Galilee was forced to land after pilots were told about the drone.The hostile craft flew southward along the Lebanese coastline when it came under the observation of the IAF.As it was flying about 8 kilometers off the coast of Haifa, IAF chief Maj.-Gen. Amir Eshel gave the order to destroy the drone, and an F- 16 dispatched a missile, blowing up its target at an altitude of 6,000 feet, IDF Spokesman Brig.- Gen. Yoav Mordechai said.It was not immediately clear whether the drone was armed. The IDF was searching for the craft’s remains in the Mediterranean Sea.“Israel is prepared to deal with any threat posed from Syria or Lebanon in the air, land or sea,” Netanyahu said afterward during a tour of the Druse village of Julis.He added that he viewed “with utmost severity the attempt to breach our borders. We will do what it takes to defend our citizens.”Hezbollah said on Thursday it had not sent the drone into Israeli airspace “Hezbollah denies that it has sent any surveillance plane towards the occupied Palestinian land,” a statement by the Iranian-backed Shi’ite group said.Asked whether Hezbollah was behind the incident, an IDF spokesman said an investigation was under way.Yaakov Lappin and Reuters contributed to this report.