"Nuclear winter," where we were all going to freeze to death after the soot from Reagan's nuclear war blotted out the sun, didn't quite happen. Rather, the Soviet Empire gave up the ghost.

“核冬天”，所谓里根的核战之后，核弹灰尘会遮天蔽日，我们将被冻死的情况，完全没有发生，相反，苏联帝国告别了那个(GC)幽灵。

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The consequences of all-out war between nations armed with nuclear weapons suddenly included the possibility of the destruction of both nations - completely and simultaneously.

拥有核武器的国家之间如果爆发全面大战，其结果可能是双方同时而彻底的毁灭。

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So, while the likelihood of an all out nuclear war is slim, there is a higher chance, thanks to rogue actors, of nuclear attacks that are not deterred by the threat of nuclear retaliation.

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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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The US already offers South Korea a "nuclear umbrella", but Cold War experts have pointed out that while nuclear deterrence may address the possibility of all-out war, it does not deter low-level incidents.

BBC: News - South Korea, US sign military plan against North 'provocations'