What role did National Security Advisor Henry Kissinger play in Nixon’s approach to Vietnam?

What role did National Security Advisor Henry Kissinger play in Nixon’s approach to Vietnam?

BOOK AND ONLY SOURCE YOU CAN USE : David F. Schmitz. Richard Nixon and the Vietnam War: The End of the American
Century. (Rowman & Littlefield Press, 2016). https://www.amazon.com/Richard-Nixon-Vietnam-War-American/dp/1442262265