"Flexible Response" was a defense strategy of the United States. This was executed by John F. Kennedy in 1961. It aims to address the Kennedy administration's suspicion of U.S. President Dwight D. Eisenhower's "New Look" policy of Massive Retaliation.
The said response needs Mutually Assured Destruction (MAD) at tactical, strategic and conventional levels, putting up the United States the skill to react to dispute over the spectrum of warfare.