First, the weapons should be intended for use only in retaliation after a nuclear attack. Second, the possession of the weapons must be a temporary expedient.

首先，这些武器应当只在遭受核袭击后反击时才使用。其次，这些武器的拥有必须是一种临时的应急手段。

《柯林斯英汉双解大词典》

Indeed, as the Soviet Union acquired vastly increased nuclear capabilities, the credibility and prudence of relying on massive retaliation gave way to our flexible response posture.

事实上，由于苏联已经拥有了大量增加的核能力，我们依靠大规模报复战略的可靠性和谨慎态度要让位于我们的灵活反应战略。

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In the early 1960s, U.S. nuclear strategists realized that a national strategy entirely reliant upon the threat of massive nuclear retaliation was not credible, that most challenges would not rise to the level of justifying nuclear response and that the Soviets would seek to take advantage of that fact.

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Second, as an alternative to defenses, national leaders adopted a strategy of deterrence, meaning any enemy foolish enough to launch a nuclear attack would suffer devastating retaliation-in-kind.

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The threat of massive retaliation in the nuclear context only deterred all-out nuclear war, but not the many other conflicts that plagued the latter half of the 20th Century that did not rise to the level of provoking a nuclear response.

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