JAPAN - RUSSIA (unresolved conflict)

Th Japanese Defense Minister, Fumio Kyuma, revealed that the impulse for Hiroshima and Nagasaki was the impending Russian seizure of mainland Japan [AP 30 June 2007].

In April 1941 [two months prior to 'Operation Barbarossa'] Russia skillfully neutralized the military threat from the East by means of signing a Neutrality Pact with Japan . Thus when the Wehrmacht swept into Russia on 22 June 1941 , Hitler was unable to mobilize a Japanese attack against Russia 's rear, despite the provisions of the 1936 Anti-Comintern Pact & 1940 Tripartite Pact.
Nonetheless, when Japan opened its campaign of aggression against the USA and Britain in the Pacific and Far East, Hitler & Mussolini gratuitously honored the Pacts by declaring war on the USA [four days after Pearl Harbor ]!
After cessation of hostilities in Europe in May 1945, the Western Allies were still heavily engaged in the Far East and US Forces were still far from realizing a successful invasion of the Japanese mainland.
However, for the Russians to leap onto Japanese soil was physically an easy operation: indeed the total occupation of Japan was such a tempting prize that moves indicating imminent abrogation of its Neutrality Pact were discerned in the summer of 1945 - prior the bombing of Hiroshima on August 6. Indeed, history records that Russian forces commenced their occupation of Japanese territories on August 8 - which they refuse to vacate to this day!
The atom bombing of Nagasaki the following day - which brought about Japan's acceptance of surrender terms on August 14 and landing of US forces on mainland Japan on August 26 - also constituted a warning to Russia not to progress further with its unprovoked aggression against a defeated Japan !
On September 2, 1945, the USS Missouri anchored in Tokyo Bay, aboard which the Japanese signed the formal terms of their surrender to [General Douglas McArthur of] the United States of America.

Thus were the Japanese spared decades of the nasty fate rendered by Russia to the nations of Eastern Europe.