古巴导弹危机是美国总统提出灵活应对的主要事件。苏联的核武装导弹在距美国港口仅90英里的古巴被发现。肯尼迪在电视讲话中明确表示，美国随时准备动用任何形式的军事力量，全世界都被核战争的威胁吓坏了。然而，当肯尼迪总统和苏联领导人尼基塔·赫鲁晓夫决定，如果美国承诺不入侵古巴，古巴导弹将被移除时，这场灾难得以避免(Schwarz, 2013)。因此，大规模报复的政策转向了“灵活应对”，目的是把世界从核战争中拯救出来，而核战争本可以摧毁许多国家。灵活反应不是一项新政策，而是为了“使军事力量适应国家和叛乱带来的挑战”而进行的一般性改变(Martel, 2015，第264页)。这是一种国防战略，带来了政治、经济和军事政策的巨大转变。大规模报复政策使美国只有两个选择;第一种选择是在地面作战，击败叛乱分子，或者在战争中使用核武器的另一种选择。
The Cuban missile Crisis was the main incident due to which American president proposed Flexible Response. The Nuclear armed Soviet missile was recognized on Cuba, which was just 90 miles away from American Port. Kennedy through his TV address made it clear that America is ready for any kind of military force and the whole world was terrified with the threat of nuclear war. However, this disaster was avoided when President Kennedy and Soviet leader Nikita Khrushchev’s decided that Cuban missile will be removed if US will promise not to invade Cuba (Schwarz, 2013). Thus, the policy of massive retaliation was shifted to ‘Flexible Response’ in order to save the world from the nuclear war that could have destroyed many nations. Flexible response was not a new policy, but was a general alteration in order to “tailor military forces to the challenges posed by states and insurgencies” (Martel, 2015, p. 264). It was a kind of defense strategy that brought a dramatic shift in the political, economic and military policies. The policy of massive retaliation had left United States with only two choices; the first choice was to fight on the ground and defeat the insurgents or to bring an alternative to the use of nuclear weapon in war.
The technology had improved since enforcement of massive retaliation. The improvements were visible in transportation and communication. This meant that US forces could be easily and effectively deployed. This was the reason that different advisors of Kennedy persuaded him that multiple options can allow him to use the force in the appropriate manner and in correct amount forces could be used.The guerilla warfare was the biggest threat to the US. The Flexible response could increase the credibility of the American forces and through this Kennedy administration would have more low intensity options to use for the war instead of all or nothing option of the massive retaliation. The policy of Flexible response also worked towards building the alliances in Middle East, Asia and Europe. Thus, Kennedy’s policy of Flexible response was dependent on the conventional and nuclear forces. It limited the use of the nuclear weapon for stopping the massive disasters (Hoffman, 2009). The rapid expansion of the communist had posed a great threat to America and people of America, because massive retaliation had resulted in destruction of the country and many innocent people had died. Kennedy focused on bringing containment of communism (Jones, 2012, p. 381). Thus, to forge a counter Guerrilla Policy, which was continuously flourishing, Kennedy came up with this new doctrine.