The last major push by the U.S. Army against American Indian tribes took place in the late 1800s. But a new report finds the military still poses a danger to American Indians. The study contends the dramatic expansion of U.S. military bases during the 20th century was largely concentrated in the same remote, arid places in the West where tribal reservations were located. That means Indians could be disproportionately exposed to toxic chemicals and unexploded bombs compared to non-Indians, according to the report by Gregory Hooks of Washington State University and a former graduate student, Chad Smith, now of Texas State University-San Marcos. Two world wars and the Cold War "pushed the United States to produce, test and deploy weapons of unprecedented toxicity," the study said. "Native Americans have been left exposed to the dangers of this toxic legacy." The study, published in American Sociological Review, is based on geography, not on actual data showing whether Indians are more often injured by unexploded bombs, Hooks said. Such studies remain to be conducted, he said.