hallmarks of Hizbullah

"“The attack does bear some of the hallmarks of Hezbollah, but we’re not in a position to make any final determination on who was responsible,” a Pentagon spokesman, George Little, told reporters."  I am not sure what the "hallmarks of Hozbollah" mean.  I am serious. When was the last time Hizbullah bombed a civilian bus? This is not a rhetorical question, by the way.  And if it has the "hallmarks" of a party, when not make a final determination of responsibility?