Japan surrendered to the Allies on 15 August, six days after the Soviet Union's declaration of war and the bombing of Nagasaki. The Japanese government signed the instrument of surrender on 2 September, effectively ending the war. Scholars have extensively studied the effects of the bombings on the social and political character of subsequent world history and popular culture, and there is still much debate concerning the ethical and legal justification for the bombings. Supporters believe that the atomic bombings were necessary to bring a swift end to the war with minimal casualties, while critics argue that the Japanese government could have been brought to surrender through other means, while highlighting the moral and ethical implications of nuclear weapons and the deaths caused to civilians.