The Department of Homeland Security today will begin an eight-day disaster-preparedness drill, testing in part how federal, state and local government agencies would respond to a large-scale terrorist attack in Seattle.

That's good for government preparedness, said Robert Harper, spokesman for the Washington Emergency Management Division.

But dozens of local activists say it's not so good. They believe the federal government has used such drills in the past to manipulate public policy, said Bob Dennis, a member of We Are Change Seattle, a local activism group.

This drill, one of the largest emergency simulations ever planned in the Northwest, will center on three fictional events in Washington and Oregon.

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The first is a simulation of a terrorist attack on downtown Seattle today. The second is a release of toxic chemicals on May 5 at the Umatilla Chemical Depot in Oregon. And the third is an explosion of a chemical tanker truck on May 6 in Whatcom County.

Soldiers, officers and government agents will not be present in downtown Seattle, said Master Sgt. David Largent, spokesman for the Washington Military Department at Fort Murray.

Instead, roughly 100 "role players" and hundreds of government officers will meet at "an urban training area" at Leschi Town at Fort Lewis, where they will set up a simulated decontamination and triage center, he said.