Do the marines know about One Piece?

[SSJ2]

Why is it that when Whitebeard announced that One Piece existed, Sengoku looked angry? Does he know what it is, or is he just worried about Whitebeard's threat behind it?

 

[Itachi]

It'll motivate the current pirates to go after it and motivate more people to become pirates

 

[Kyo]

The Gorosei might have some idea, maybe.

 

[Alex Boss]

The marines don't want to think about the existence.

 

[Captain Cadaver]

What Itachi said. The only people I see having some knowledge of OP outside of Roger's crew is the Gorosei, since they already knew about the True History.