Once Germany & Italy had been defeated, the full might of Russia, China and the UK would have seen off Japan. BTW, the US never declared war on Germany in WW2, it was Hitler who declared war in support of the fellow fascist Hirohito. It was the only time Hitler declared war, usually he just marched in. The US at that time was strongly independent due to the large ethnic German population (such as the Drumf family quietly operating their brothels).I don't see how the UK could have defeated Japan