Yikes! Even IF the parts are indeed made in the USA, they are then being shipped to China on a boat, which is polluting the environment to be assembled. The assembled phones are then shipped back to the USA on a boat, which again is polluting the environment.
So, yes it being assembled in another country is just as big of a deal as if the parts were made in another country. Now, if the USA is the only place the parts can be manufactured, then make them here and ship them to the countries where the phones will be sold to be assembled. In other words, assemble phones in the USA that are going to be sold in the USA, assemble phones that are going to be sold in China in China, assemble phones that are going to be sold in Canada in Canada, etc. Doing this will help spur the local economy of each of these countries, which means Apple could end up selling more phones there.