Instructions: Generate a correct and concise answer for the question based on the words in the context.
Input: Context : Tad J. Oelstrom (born February 14, 1943) is a retired United States Air Force Lieutenant General who now serves as the Director of the National Security Program at the John F. Kennedy School of Government, Harvard University.
Question : With which military branch did Tad J. Oelstrom serve with?
Output:
United States Air Force