The changing world order that the war had brought about, in particular the growth of the United States and Japan as naval powers, and the rise of independence movements in India and Ireland, caused a major reassessment of British imperial policy. Forced to choose between alignment with the United States or Japan, Britain opted not to renew its Japanese alliance and instead signed the 1922 Washington Naval Treaty, where Britain accepted naval parity with the United States. This decision was the source of much debate in Britain during the 1930s as militaristic governments took hold in Japan and Germany helped in part by the Great Depression, for it was feared that the empire could not survive a simultaneous attack by both nations. Although the issue of the empire's security was a serious concern in Britain, at the same time the empire was vital to the British economy.