Flexible response Flexible response was a defense strategy implemented by John F . Kennedy in 1961 to address the Kennedy administration ' s skepticism of Dwight Eisenhower ' s New Look and its policy of Massive Retaliation . Flexible response calls for mutual deterrence at strategic , tactical , and conventional levels , giving the United States the capability to respond to aggression across the spectrum of warfare , not limited only to nuclear arms . History . The New Look policy , though initially useful , quickly became obsolete with the introduction of inter - continental delivery systems that undermined the credibility of a deterrence threat . The cornerstone of U . S . and European defense strategy was then threatened as the U . S . could no longer rely on nuclear threats to provide security for it and its allies . John F . Kennedy won the presidency by touting that the Republican Party had allowed the U . S . to fall behind the Soviets into a Missile gap . Upon entering office Kennedy cited General Maxwell Taylor ' s book " The Uncertain Trumpet " to Congress for its conclusion that massive retaliation left the U . S . with only two choices : defeat on the ground or the resort to the use of nuclear weapons . Technology had improved since massive retaliation was adopted . Improvements in communication and transportation meant U . S . forces could be deployed more effectively , quickly , and flexibly than before . Advisers persuaded Kennedy that having multiple options would allow the president to apply the appropriate amount of force at the right place without risking escalation or losing alternatives . This would improve credibility for deterrence as the U . S . would now have low - intensity options and therefore would be more likely to use them , rather than massive retaliation ' s all - or - nothing options . Flexible Response was implemented to develop several options across the spectrum of warfare , other than the nuclear option , for quickly dealing with enemy aggression . In addition , the survivability of the retaliatory capability was stressed , leading to the diversification of the strategic force , development of the strategic triad , and half the Strategic Air Command force being put on permanent alert status . The Kennedy doctrine did not include the ability to fight nuclear wars because of the idea that it would undermine deterrence , was technologically unworkable , would fuel the arms race , and was not politically feasible . Importance was also placed on counterinsurgency and the development of unconventional military forces , unconventional tactics , and “ civic action ” programs . Stages in the Flexible Response . A staged plan was devised to counter any Soviet military action other than a first strike . It consisted of three stages : Direct defense : In case of a conventional Soviet attack ( meaning non - nuclear or this would be considered a first strike ) initial efforts would be to try and stop the Soviet advance with conventional weapons . This meant that the foreseen Soviet attack on West - Germany would be tried to be forced to a halt by NATO ' s European forces , Allied Command Europe . Deliberate Escalation : This phase was entered when conventional NATO forces were succumbing under the Soviet attack . This was actually expected as intelligence indicated Soviet divisions outnumbered NATO divisions by far . In this phase NATO forces would switch to a limited use of nuclear weapons , such as recently developed tactical nuclear weapon s ( like nuclear artillery ) . General Nuclear Response : This was the last phase or stage which more or less corresponded to the mutual assured destruction scenario , meaning the total nuclear attack on the Communist world . If the Soviets had not already done so , this would make them switch to all - out attack as well . Development of the strategic triad . By 1960 , the United States had three means of strategic forces : ICBM s , SLBM s , and strategic bomber s . This triad made it possible for the United States to impose unacceptable damage to the Soviet Union with one strategic force independent of the other two forces . These different forces had their advantages and disadvantages . Bombers could deliver large payloads and strike with great accuracy , but were slow , vulnerable while on the ground , and could be shot down . ICBMs are safe in their underground silos while on the ground , but were less accurate than bombers and could not be called back when launched . Submarines were least vulnerable but were also least accurate and communication could be poor at times . Each of these forces provided the United States with different options to tailor their response to the situation . Two - and - a - half war doctrine . Part of Flexible Response was the strategy of being able to fight over the entire spectrum of violence by developing diverse forces for different types of warfare . This meant being able to fight multiple wars simultaneously ; specifically , the US should have the peacetime capability to fight two large regional wars and a small brushfire war at the same time . The consequence of this was to increase recruiting , investment , and research for the US force posture . Assured Destruction . The strategic doctrine for Kennedy ’ s Flexible Response was Assured Destruction . Flexible response made second strike capability its guiding principle of deterrence . In the event of Soviet nuclear aggression , the Soviets would know that enough U . S . nuclear capability would survive their strike to destroy their cities and industry . Robert McNamara argued for the definition of what was “ unacceptable ” to the enemy as the destruction of 50 % of industry and 25 % of the population . Deterrence depended on influence to show that violence and aggression did not pay , and being explicit about the level of destruction the US was willing to inflict on the enemy was one way to illustrate this point . Assured Destruction relied on deterrence by punishment , precision , and credibility . No - Cities doctrine . Defense Secretary McNamara sought to limit damage to the U . S . by developing a separate strategy for offense and defense . The offensive strategy was one of Counterforce , seeking to destroy Soviet military installations and hardware and thus disable this hardware before it could be used . In a 1962 speech to the University of Michigan , Ann Arbor , McNamara announced that the U . S . would refrain from striking Countervalue targets ( cities ) early in nuclear war , reserving such force later in war should the Soviets not show similar restraint . This would not only induce the Soviets to spare American cities , but would secure the United States bargaining advantage by holding hostage something that the Soviets might want to keep . The defensive strategy involved developing a system to intercept incoming Soviet missiles . Bombers could be easily shot down , but missiles still remained a credible threat . The United States began developing anti - ballistic missile program , modifying its Nike missiles to intercept incoming missiles . Ultimately this program was abandoned by the adoption of the anti - ballistic missile treaty .