I don't know what Sony Ericsson's policy is but you might be surprised at how many well established manufacturers do not offer international warranties with their products.

When I worked in retail, I once tried to sell an HP printer to a young English couple who intended to eventually take it home with them. I was fairly sure that HP would offer an international warranty, but I told the customers that I would double check because I didn't want to sell the machine to them on false pretences. As it turned out, the sales rep from HP advised me that the warranty on most of their consumer products was only valid in the country of purchase. I understand that others have had similar experiences when purchasing other electronic and camera products.