On July 26, 1945, the United States, Britain and China issued the Potsdam Declaration, which called on Japan to surrender. At a press conference on July 28, Prime Minister Suzuki Kantarō said that the government would mokusatsu it. The Dōmei news agency probably translated the word as “ignore,” and the foreign press took it as “reject.”
The Soviet declaration of war treated the answer as Japan’s refusal. Whether Suzuki meant a refusal at all is disputed.