Campaigning against Wilson's policies, Harding won election in 1920 and took office in 1921. Harding repudiated the Treaty of Versailles, and the United States never joined the League. Secretary of State Charles Evans Hughes led the negotiations that resulted in the 1922 Washington Naval Treaty, under which the major naval powers agreed to avoid a naval arms race. Efforts for disarmament would continue after 1922, leading to the signing of the 1930 London Naval Treaty. European war debts and reparations also emerged as a major issue in the 1920s; the U.S. consistently refused to forgive the debts, but Harding, Coolidge, and Hoover all reached agreements to lower the burden of debts on various European countries. Coolidge's main foreign policy initiative was the Kellogg–Briand Pact, under which the signatories agreed to renounce war as an "instrument of national policy". The Great Depression began during Hoover's tenure, leaving the worldwide economy in crisis. In the midst of the depression, Japan invaded Manchuria and Adolf Hitler came to power in Germany.