main character was a cia officer who hunts terrorists in usa
The main character in Hunter by Lazlo Z. starts out in the CIA.
Why he is permitted to hunt terrorists within the USA is part of the story.
I thought they were not permitted to operate domestically.
The CIA has long proven its eagerness to utterly ignore the law. The list of their actions within the US judged to be illegal and often unconstitutional is both long and infamous.