The Department of Homeland Security is suspending plans to conduct bioterrorism drills near the Kansas-Oklahoma border over concerns about their impact on grounds Native American tribes consider sacred.

Homeland Security spokesman John Verrico said in an email Thursday the tests were suspended over objections to them taking place at the Chilocco Indian Agricultural School. The school operated from the late 1800s until 1980 and was one of several federally run schools where the government tried to assimilate Native American children. Tribes said the agency wasn't protecting a site with religious and cultural significance.

The tests involved release of inert materials to evaluate the ability of buildings to protect occupants from biological hazards. Verrico says the work remains important and the agency is looking for another location.