A mob in Lebanon attacked the office of a Sunni Muslim religious leader in the northern city of Tripoli, smashing in windows early on Wednesday, reports said. The assailants then moved to one of the city’s main squares and set fire to the municipality’s Christmas tree. The violence indicated that the tensions that recently gripped the Lebanese capital, Beirut, over an online video deemed offensive to the country’s Shiites are spreading to Tripoli, the country’s second-largest city.