CAMP ATTERBURY, Ind. -- Normally, First Army observer controller/trainers train National Guard and Reserve Soldiers for missions in locations such as Afghanistan, Kosovo and Cuba.

This month, however, they are leading training for a realistic disaster-response exercise right here at home.

Approximately 5,500 National Guard service members, Department of Defense civilians and federal and state agencies from across the country are participating in the Vibrant Response exercise, which simulates five-kiloton improvised nuclear devices detonating in two American cities. The exercise tests the capabilities of the nation's emergency response network, including military chemical, biological, radiological and nuclear response forces, as well as command and control response elements.

Before the exercise kicked off July 27, First Army Soldiers attended a two-day Observer Controller/Trainer Academy to learn their roles and responsibilities, which include watching a unit plan, move, execute and recover; keeping the unit operationally focused; and using doctrine, examples and feedback during "hot washes" discussions that review the effectiveness of the unit's actions and ways to improve them.

"I'm primarily evaluating ministry teams and also helping out with other sections as needed," said Chaplain (Maj.) Murray Phillips, a First Army Soldier from Whiteside, Mo. "I'll be evaluating how ministry teams integrate with their staffs…and see what their plans are in taking care of the needs of their Soldiers during the mass casualty situation. Sometimes that gets overlooked."

Phillips said he is excited about his role in Vibrant Response.

"It's going to be an interesting learning experience," he said. "There are a lot of people here with experience to draw upon and a lot of expertise to offer."

Maj. Diane Moncrief, a First Army logistics plans officer from Hampshire, Ill., said she expects to learn a lot during the exercise.

"I feel that I can improve my expertise in many areas by being an OC/T," she said. "My role is to observe the Task Force Headquarters logistics plans officer and, having been in exercises before, I know the difference a good OC/T can make. I'm excited about the opportunity."

Attending the O/C-T Academy was very beneficial, Moncrief added.

"I learned more about what the roles and responsibilities of an OC/T are for this particular exercise," she said. "The units we are observing are responding to a nuclear threat, and we will observe how they respond to different incidents in that threat and then give them feedback."

Pfc. Brittany Gaura of Davenport, Iowa, said the OC/T Academy provided good training information, and she welcomes the chance to put her newfound knowledge to use.

"It's a good opportunity to be a part of this," she said. "It's a good learning experience for me. I'm glad to get a chance to do it, and I'm excited."

First Army mobilizes, trains, validates, deploys and demobilizes all Army National Guard and Army Reserve forces throughout the continental United States, providing trained and ready forces for diverse missions.