Mezue nkebi ahịrịokwu na-esonụ: United States na Soviet Union kwụsịrị agha ahụ site n'iji ngwá agha ọhụrụ lụso ndị Japan ọgụ (n'aka United States) nakwa site n'ịwakpo Manchuria (n'aka Soviet Union). N'August 6, 1945, otu ụgbọelu B-29 nke ndị America, bụ́ "Enola Gay", tụrụ bọmbụ atọm mbụ e ji lụọ agha na Hiroshima, na-egbu ọtụtụ iri puku mmadụ ma mee ka obodo ahụ tọgbọrọ n'efu. N'abalị itoolu n'ọnwa Ọgọstụ n'afọ 1945, Soviet Union kwụsịrị nkwekọrịta ya na Japan na-ekwekọrịta ịghara ịwakpo ha.
wakporo ndị Japan na Manchuria, na-emezu nkwa ya na Yalta Conference ịwakpo ndị Japan n'ime ọnwa atọ mgbe njedebe nke agha na Europe. Ọ bụ ìgwè ndị agha Soviet atọ wakporo ebe ahụ. N'otu ụbọchị ahụ, United States tụrụ bọmbụ atọm nke abụọ ka nke ahụ njọ na Nagasaki.