I have a question and I am hoping someone here can answer it. When I read the book underboss by Peter Maas that the killing of Phil Testa was by a method forbidden by Mafia rules, the assassins used a bomb. Sammy Gravano also states that the bomb under Frank DeCicco's car wasn't taken seriously because that the Mob in America doesn't allow it. However, I am always seeing reports about American Mafiosos using explosives to kill their target such as in the case of Danny Greene who was an Irish gangster in Cleveland who very much upset his Italian partners.

What i want to know is if the mafia approves of using bombs as a method of assassination or if there are rules against their use.