Hizbullah is bolstering its presence in south Lebanon villages with non-Shi'ite majorities by buying land and using it to build military positions and store missiles and launchers, The Jerusalem Post has learned. The decision to build infrastructure in non-Shi'ite villages - where Hizbullah has less support - is part of the group's post-war strategy under which it has mostly abandoned the "nature reserves," forested areas in southern Lebanon where it kept most of its Katyusha rocket launchers before the Second Lebanon War. Behind the change is the mandate given to UNIFIL by the United Nations after the war in 2006. According to the mandate, the peacekeeping force can patrol freely throughout southern Lebanon but cannot enter villages or cities without being accompanied by soldiers from the Lebanese Armed Forces, which regularly tips off Hizbullah ahead of the raids. News of the change in Hizbullah strategy came as Israel is trying to persuade the UN to strengthen UNIFIL's mandate to give it the right to patrol the villages freely. "Hizbullah is moving into every town that it can," a senior defense official told the Post. "This is in order to evade UNIFIL detection." On Thursday, Lebanese complained they were receiving recorded phone messages from Israel promising "harsh retaliation" for any future Hizbullah attack. The automated messages also warn against allowing Hizbullah to form "a state within a state" in the country. The phone messages end with the words: "The State of Israel." There was no immediate confirmation from Israel, though similar reports surfaced of Israeli phone campaigns during the 2006 war trying to persuade Lebanese not to support Hizbullah. Lebanon's official National News Agency said residents in the country's south and east, as well as in Beirut reporting receiving the calls. It said Telecommunications Minister Jibran Bassil contacted the United Nations to complain, calling it a "flagrant aggression against Lebanese sovereignty." Also Thursday, defense officials warned that with the prisoner swap completed, Hizbullah would no longer need to restrain itself and might decide to avenge the assassination of the group's operations chief, Imad Mughniyeh, who was killed by a car bomb in Damascus last February. As a result, the IDF has slightly increased its level of alert along the border, based on the assessment that even if a retaliatory attack took place abroad the violence would spread to the Israeli-Lebanese border.