Russia and China
Id have to say Russia & USA.Ideologically opposed & both paranoid of the others influences on other countries.
During World War II the primary enemies of the Allies (of which we were a part) were Japan and Germany. There were also other minor Axis countries which were part of the war.
The primary enemies of the allies during world war 2 were Germany, Japan, and Italy. Together, those three countries were called the "AXIS" powers.
USA, UK, and USSR were Allies. Germany, Italy and Japan were Axis enemies.
It all depends on the problem for why the war broke out. If a country tried to take over, then that countries allies would most likely be on that side and would be known as "enemies", while the other side would be known as allies. Some past allies would probably be allies again, like US, UK, France, Canada, etc.
allies war of 1812
The Allies and the Entente.
Germany, Italy, Japan and Hungary/Austria.
Germany, Italy, Japan
Britan was one of New Zealand's allies in world war 2.
Germany's main enemies in World War 1 were Britain, France, Italy, and Russia. America too, but we joined the war later than any of the other Allies.
the russians
In basic terms, some of yesterday's enemies became new allies, and some former allies became enemies, although not in an outright way. Japan, Italy, and West Germany became Western allies. China, North Korea, East Germany, and the former Axis countries of Eastern Europe lined up with the USSR. It should be remembered that most of these alliances were involuntary on both sides, but the Free World countries tended to have a greater freedom of choice than the Communist countries. As in World War 2, a few countries were able to remain neutral in the Cold War.