American carriers travel with an unseen companion: at least one nuclear-powered attack submarine.

美国航母有水下隐形群组伴随：至少一艘核动力攻击潜艇。

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A u. s. navy nuclear-powered attack submarine under heavy escort has arrived back at its home port of Guam after a fatal accident at sea.

美国旧金山号核动力攻击潜艇在发生致命事故以后，在严密的护航之下返回在关岛的基地。

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The 97m (318ft)-long craft is the UK's newest nuclear-powered attack submarine and joined the Royal Navy fleet in August 2010.

BBC: Able Seaman Ryan Samuel Donovan

In an exhibition marking the 80th anniversary, Beijing's Military Museum displays what Chinese official websites say is a model of a new nuclear-powered attack submarine, the Shang.

ECONOMIST: China's military might

The proposed plan would retire seven cruisers early, delay construction of the next large-deck amphibious warfare ship by one year, cancel the second Virginia-class nuclear-powered attack submarine (SSN) in 2014, delay construction of two smaller amphibious warfare ships, and reduce procurement of littoral combat ships by two and joint high speed vessels by eight.

CENTERFORSECURITYPOLICY: Section IV: Building a Two-MRC Force for the 21st Century