Read this: Unlike the Federal Bureau of Investigation (FBI), which is a domestic security service, CIA has no law enforcement function and is mainly focused on overseas intelligence gathering, with only limited domestic collection. Though it is not the only U.S. government agency specializing in HUMINT, CIA serves as the national manager for coordination and deconfliction of HUMINT activities across the entire intelligence community. Moreover, CIA is the only agency authorized by law to carry out and oversee covert action on behalf of the President, unless the President determines that another agency is better suited for carrying out such action. It can, for example, exert foreign political influence through its tactical divisions, such as the Special Activities Division.
Now answer this question, if there is an answer (If it cannot be answered, return "unanswerable"): What is the only agency that is authorized to carry out action on behalf of the president?
CIA