Source: <http://www.businessweek.com/news/2014-10-21/the-rest-is-mystery-as-swedes-chase-possible-russian-sub>

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> Is it a submarine? Is it Russian? And what’s it doing off the coast of Sweden?  
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>  The swirling nautical whodunit in the Baltic Sea brought back memories of Cold War **fact and fiction**, fueling the hypothesis among jittery neighbors that President Vladimir Putin’s Russia is making more regional trouble.  
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>  That is, if the vessel is one of his.
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> 

How do you grammatically understand that phrase?