SEATTLE (CNN) -- In addition to hundreds of very visible Army National Guard troops called-up because of the civil disturbances in Seattle, more than 160 active duty military personnel, including a small number of Special Forces troops, were sent to Seattle by the Defense Department for the meeting of the World Trade Organization.

The military mission, according to the Pentagon, is to "provide support" to the FBI, Federal Emergency Management Agency (FEMA), U.S. Secret Service and other government agencies responsible for security there. The military specialists are in place largely to provide expertise and assist in coordinating a federal response in the event of a terrorist attack during such a high-profile event.

According to Defense Department documents obtained by CNN, 131 U.S. Army, 27 U.S. Air Force, and eight U.S. Navy personnel were sent to Seattle to perform roles from ordnance disposal to standing by for possible chemical or biological attack by terrorist groups.

Four special forces troops from the Joint Special Operations Task Force were deployed to Seattle to be on hand to advise FBI "crisis support" agents in the event of a catastrophic terrorist event involving chemical or biological weapons or hostage taking. Two of the four special operations experts have since left the city, according to an informed Pentagon official who spoke on
the condition that he not be named.

Fifty-five military Explosive Ordnance Disposal (EOD) teams, along with 25 explosive-detecting dogs and their handlers, were sent. The soldiers are "operating in civilian attire -- keeping a low presence," the Defense Department documents say.

Troops there are from various military fiefdoms including the U.S. Special Operations Command, the U.S. Forces Command, the U.S. Army Biological-Chemical Command, the U.S. Air Force Security Forces Command and the U.S. Joint Forces Command.

Eight divers, making up two Navy dive teams, were sent to provide support to the Secret Service for President Clinton's visit, which ended Thursday. The action is not unusual for presidential security.

The Department of Health and Human Services and FEMA have set up a "staging area" for their operations at the U.S. Naval Reserve Center-Lake Union in Seattle. Eight military personnel are assigned to that site. The HHS-FEMA site is pre-positioned to respond to major health catastrophes such as a biological agent attack, according to a well-informed source.

The "Domestic Military Support," or "DOMS" as it is known at the Pentagon, is provided through the Office of the Secretary of Defense and the Office of the Chairman of the Joint Chiefs of Staff at the request of other federal agencies.