My D70s along with 18-70mm Nikon zoom lens, SB-600 flash, were all made in Thailand. My Nikon 70-300 zoom lens is made in Japan. These were all purchased in the US, not 'grey market' products. Beware of grey market products (more on Nikon's website).
My older Nikon products like the F2, FM2, Nikkormat EL, and some Nikkor lenses for film, were all made in Japan.
All products require the country of manufacture to be clearly marked on the product, and just as is the case with automobiles (BMW, Mercedes, etc), the country of manufacture is a Marketing decision based on product volumes, demand, labor considerations, political climate, etc. - all factors beyond the consumers' control.
I have no question in my mind that in the near future, Nikon will shift some of their production to China, and wherever the new emerging labor markets will be. As long as the QA requirements are stringent, this should not be an issue.
Remember the old "Assembled in Mexico"? We don't see much of that these days