First of all, please don't be paranoid, Japan has been one of the largest military spender in recent decades, and their military is second to none in the region. They are also capable of assembling nuclear weapons in a matter of months with their existing nuclear facilities and plutonium stocks. Do a little bit of research on your own before you sound ignorant. Secondly, there are huge US bases in Japan and nearby Pacific islands, just there to watch over the region. Thirdly, ask yourself WHY on earth would anyone bother to attack Japan unprovoked? Is Japan sitting on mountains of oil? Of gold and minerals? Will China be after those useless US$ assets in Japan's banks while it is desperately trying to unload its own US reserves? Use those little grey cells, please.