WASHINGTON — A former Air Force sergeant who defected to Iran did severe damage to American intelligence operations, and is suspected of revealing the names of double agents run by United States military intelligence, some of whom had their cover blown after her defection, according to former counterintelligence officials.

Monica Elfriede Witt, 39, the former Air Force counterintelligence agent, is also accused of exposing the names of eight American military counterespionage agents, and she had knowledge of how the United States intercepted foreign communications, the government’s most important stream of intelligence. She also knew the inner workings of American military operations across the Middle East.

Ms. Witt’s indictment on charges of providing American secrets to Tehran was made public this week. Her alleged activities came at a time when American intelligence operations were already plagued by the penetration of a top-secret communications network by China and Iran that had deeply damaged spying operations abroad.

When Ms. Witt defected to Iran in August 2013, “defensive measures” were taken in an attempt to reduce the damage she could inflict, according to a former senior intelligence official who spoke on the condition of anonymity, like others involved in the case, because of its sensitivity.