On 2 October, the Lytton Report was published and rejected the Japanese claim that the Manchurian invasion and occupation was an act of self-defense, although it did not assert that the Japanese had perpetrated the initial bombing of the railroad. The report ascertained that Manchukuo was the product of Japanese military aggression in China, while recognizing that Japan had legitimate concerns in Manchuria because of its economic ties there. The League of Nations refused to acknowledge Manchukuo as an independent nation. Japan resigned from the League of Nations in March 1933.