Final answer:
The Naval Investigative Service concluded in its initial report that the CIA had participated in illegal surveillance operations and wiretapping of antiwar organizations within the United States.
Step-by-step explanation:
The Naval Investigative Service, which was involved in the Watergate investigation, concluded in its initial report that the CIA had participated in illegal surveillance operations and wiretapping of antiwar organizations within the United States. This finding led to a series of investigations that uncovered various CIA plots, secret payments, and attempts to destabilize foreign countries, such as Cuba. The initial report revealed the extent to which the CIA had violated its mandate by conducting domestic operations.