The President would most rely on the secretary of state for analysis of another nation's political situation and for advice on how to handle diplomatic situations with that country,
The President of the United States is the one who nominated a secretary of state.
The Secretary of State is a senior official of the federal government of the United States of America, and as head of the United States Department of State, is mainly concerned with foreign policy and is regarded as the U.S. government's equivalent of a Minister for Foreign Affairs.