Who is Tommy Karr from Stephen Coonts' Deep Black and what is their importance?

Tommy Karr, whose real name is Kjartan Magnor-Karr, works as an NSA Deep black operative. Karr is assigned to the Desk Three covert operations group of NSA. He is in London to accompany Charles Dean when he meets Gordon Kensworth. Unfortunately, the meeting doesn't go as planned and Kensworth is shot in front of them.
Karr is also present at the Eiffel Tower when the terrorist attack begins and plays a large part in foiling the terrorists' plan.