In 1920, the first assembly of the League of Nations established an Advisory Committee on Traffic in Opium and Other Dangerous Drugs to assist and advise the league's council. Under the league's auspices, in 1925, 1931, and 1936, various international drug control conventions were developed to counter an already dangerous threat posed by drug abuse and illicit drug trafficking. In 1946, the United Nations assumed the drug control functions of the League of Nations, as the league's Advisory Committee's functions were transferred to the UN Commission on Narcotic Drugs. The commission gives priority to promoting greater regional and interregional cooperation among drug law enforcement agencies. The UN prepared the 1961 Single Convention on Narcotic Drugs, which consolidated most of the earlier international instruments. It simplified and streamlined the control machinery. In spite of increased international efforts to control drugs, however, drug trafficking and abuse has increased, as traffickers have developed a widening diversity of routes and used violence in attempts to preserve and expand their domains. The UN has continued to press for greater international control efforts through the 1984 Declaration on the Control of Drug Trafficking and Drug Abuse, the Draft Convention Against Illicit Traffic in Narcotic Drugs and Psychotropic Substances, and the International Conference on Drug Abuse and Illicit Trafficking in 1987.