The submarine is China's first step to build a sea-based nuclear force, which can provide the country with the valuable 'second strike' capability.

潜艇是中国建立海-建核力量的第一个步骤，能提供国家拥有宝贵的‘第二次打击’能力。

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As nuclear arsenals grew, each of the two main sides in the Cold War gained second strike capability, rendering a surprise attack moot.

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China is vehemently opposed to the US plans for a missile defence system because of the threat it will pose to its own tiny second-strike capability.

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Nevertheless, such patents are now handed out regularly, creating an arms race amongst tech companies to have a second-strike capability in the event their own innovations are challenged.

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