Although the poster did not identify the ship in the poster as the Cheonan, the South Korean corvette sunk in March, it raised suspicions that North Korea may have begun bragging about the sinking for domestic propaganda purposes, said Radio Free Asia, which released a photograph of the poster.

With the caption, ''If they attack, we will smash them in a single blow'', the poster shows the red fist of a North Korean sailor splitting an enemy ship.

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I found an actually picture of the poster here:


 

So it looks as though NorKor is denying this to the outside world and bragging about it internally.  Not cool.