What is a civilization? Where does the line between a nation and a civilization diverge? When does a nation become a civilization? What is the difference between a nation and a civilization?
You could make a fairly strong argument for America being a civilization, as well as almost any other country on the earth.
As for Korea suggesting that their civilization is 10,000 years old, I'd like to believe that it's a ridiculous claim. Any civilization that existed there most likely did not consider themselves Korean.
United State of America is more like part of the modern "Western Civilization" and Western Civilization had been last 700 years after renaissance. America is part of the Western Civilization. (greek and Italian are considerly not part of Western Civilization. only France, Germany, Great Britian, Holand and Sweden are part of it.)
PS: russian and serbian, turkish are not part of it too
and yet Asian were never been civilized before. chinese claim they have 4000 years of history but they aint. they can only tell lies and make fake evidence.