Answer:
The US government’s skillful use of research and intelligence enabled a vital spy mission.
Step-by-step explanation:
The author describes the CIA, which is the foreign intelligence service of the United States, as extraordinarily competent. This means that the U.S. government used research and intelligence skillfully.
This, coupled with the help of a Soviet informant, enabled the U.S. government, according to the author, to start a vital spy mission in Berlin.