American Indian Movement (AIM), Native American civil-rights activist organization, founded in 1968 to encourage self-determination among Native Americans and to establish international recognition of their treaty rights. In 1972, members of AIM briefly took over the headquarters of the Bureau of Indian Affairs in Washington, D.C. They complained that the government had created the tribal councils on reservations in 1934 as a way of perpetuating paternalistic control over Native American development. In 1973, about 200 Sioux, led by members of AIM, seized the tiny village of Wounded Knee, S.Dak., site of the last great massacre of Native Americans by the U.S. cavalry (1890). Among their demands was a review of more than 300 treaties between the Native Americans and the federal government that AIM alleged were broken. Wounded Knee was occupied for 71 days before the militants surrendered. The leaders were subsequently brought to trial, but the case was dismissed on grounds of misconduct by the prosecution. AIM also sponsored talks resulting in the 1977 International Treaty Conference with the UN in Geneva, Switzerland.