all international kindles are shipped from the US. ebooks must be bought from US too. the UK ebooks rights are ONLY for the UK, same with FR and DE. the US store handles american and international rights. other markets not quite big enough yet.

if you're thinking about physical books, that's wrong too. a book sold in both the US and UK shop will usually have a different publisher, so which one you get depends on where you ordered it, not where you live.