What would happen in this amazing world war?

Ok....lets say N. Korea nukes and then invades S. Korea....the US and UK send aid and weapons. While China and Russia supply N. Korea. The US makes an excuse to go to war with N. Korea and helps S. Korea. The UK helps too. China finds an excuse and declares war on the US. Then Iran takes its chance and quickly attacks all US and NATO forces near the Middle East. France, Germany and Israel fight Iran, while Russia supplies Iran. Then Russia invades and conquers France and Germany. While most of their forces are away. What would be the outcome? Who'd win?