sentences:  Every bit of destructive power that could be delivered to the enemy's interior was considered advantageous in maintaining deterrence and would become the basis of the US strategic arsenal.Flexible response was a defense strategy first implemented by John F. Kennedy in 1961 to address the Kennedy administration's skepticism of the policy of massive retaliation in the face of strike options limited to total war during the Cuban Missile Crisis.That, along with cost, increasingly-accurate targeting, multiple warheads per delivery vehicle, and a desire for greater flexibility in targeting especially with respect to increasing sensitivity to collateral damage in some scenarios, began the trend to reducing individual warhead yields in strategic weapon systems.