Fail Deadly was more commonly known as
Massive Retaliation, a
military strategy which would ensure that a
United States counter strike against the
Soviet Union would be conducted by a higher factor. Basically, if the Soviets launched one missile at the United States, they would get 10 in return. If they launched 10, they would get 100 in return, and so on. The term is a reference to
fail safe.
See also (and consider redirecting this page to) Mutual assured destruction