The International Opium Convention, signed at The Hague on January 23, 1912 during the First International Opium Conference, was the first international drug control treaty. It was registered in League of Nations Treaty Series on January 23, 1922. The United States convened a 13-nation conference of the International Opium Commission in 1909 in Shanghai, China in response to increasing criticism of the opium trade. The treaty was signed by Germany, the United States, China, France, the United Kingdom, Italy, Japan, the Netherlands, Persia, Portugal, Russia, and Siam. The Convention provided that "The contracting Powers shall use their best endeavours to control, or to cause to be controlled, all persons manufacturing, importing, selling, distributing, and exporting morphine, cocaine, and their respective salts, as well as the buildings in which these persons carry such an industry or trade."