Italy has clamped unprecedented security measures at the Vatican and other major Christian landmarks because of Christmastime attack fears, NBC said Thursday. According to their report, Israeli security service Mossad warned that "an important symbol of Christianity" could be the target of an attack between Christmas and New Year's. Italy tightened security at some 8,000 sites - including the famous St Peter' Square -, Interior Minister Giuseppe Pisanu has told the AFP. Officials in the northern Italian city of Pisa also tightened security around its legendary Leaning Tower. An Italian police official, however, has described the threat as "credible" rather than specific, meaning there was more information on the type of attack than about where or when it was most likely to occur.