What doctrine replaced reliance on massive retaliation with a flexible response strategy to deter and respond to conventional threats?

• A. Massive retaliation
• B. Flexible response
• C. Containment
• D. Mutually Assured Destruction

Answer: (B)

The idea being tested is a strategy that expands the range of possible responses to threats, rather than relying on one all-encompassing option. Flexible response shifts away from the idea that any aggression must be met with massive nuclear retaliation, and instead prepares a spectrum of responses—from conventional military force to tactical or strategic nuclear options—matched to the level and nature of the threat. This approach sought to deter both large-scale war and smaller, conventional confrontations by ensuring the United States could respond credibly without automatically escalating to full-scale nuclear war.

Massive retaliation embodies the older concept: respond to any aggression with an overwhelming nuclear punishment. While it deterred certain threats, it proved inflexible for conventional wars or limited conflicts where nuclear escalation would be disproportionate or catastrophic. Mutually Assured Destruction is the broader deterrence logic that a nuclear war would be devastating for all sides, but it isn’t a particular doctrine for how to respond across a range of conflicts. Containment is the long-term policy of preventing the spread of communism, not a specific escalation plan for deterring and countering conventional threats. Flexible response is the doctrine that fits the question: it replaces the single, all-or-nothing approach with a graduated set of options to deter and respond appropriately to different kinds of threats.