Too many people are overly concerned with the country of origin for their cameras. Nikon is not going to jepordize their reputation by selling an inferior product from a factory in another country. If you look at all the manufacturers, Fuji produces more cameras in Japan than other companies (my observation). Usually, the most expensive "Flagship" professionial models are made in Japan.
This is true of Canon, Nikon, Minolta, Olympus, etc. etc. etc . . . .
A Korean 5400 should perform just fine.