Complex sentence: Bell Telephone Laboratories started the development of Fault Tree Analysis during early sixties for the U.S. Air Force Minuteman System (Intercontinental Ballistic Missiles and Bombers) afterwards U.S. nuclear power plants and Boeing Company used the system extensively.
Split into simpler sentences: Bell Telephone Laboratories started the development of FTA during early 60's for the U.S. Air Force Minuteman System (Intercontinental Ballistic Missiles and Bombers). Later, U.S. nuclear power plants and the Boeing Company used the system extensively.