The Soviet–Japanese Neutrality Pact , also known as the Japanese–Soviet Non-aggression Pact , was a non-aggression pact between the Soviet Union and the Empire of Japan signed on April 13, 1941, two years after the conclusion of the Soviet-Japanese Border War. The agreement meant that for most of World War II, the two nations fought against each other's allies but not against each other. In 1945, late in the war, the Soviets scrapped the pact and joined the Allied campaign against Japan.

A non-aggression pact or neutrality pact is a treaty between two or more states/countries that includes a promise by the signatories not to engage in military action against each other. Such treaties may be described by other names, such as a treaty of friendship or non-belligerency, etc. Leeds, Ritter, Mitchell, & Long (2002) distinguish between a non-aggression pact and a neutrality pact. They posit that a non-aggression pact includes the promise not to attack the other pact signatories, whereas a neutrality pact includes a promise to avoid support of any entity that acts against the interests of any of the pact signatories. The most readily recognized example of the aforementioned entity is another country, nation-state, or sovereign organization that represents a negative consequence towards the advantages held by one or more of the signatory parties.