[Photo by Dewald Aukema/For China Daily]

Defining point

Vietnam remains the defining point in his career. Some such as the late Christopher Hitchens have held him responsible directly for hundreds of thousands of deaths. Ferguson's book makes clear his efforts to stop the war from 1965 onward.

"I think that is where the book makes an important contribution. From that point Kissinger is trying to end the war and extricate the US from the mess," he says.

Ferguson says Kissinger, who appeared on the cover of Time magazine 15 times, feels frustrated by the state of US-China relations and by the downgrading of the role of secretary of state.

"Nowadays, the job is almost the consolation prize for the failed presidential candidate and neither (John) Kerry nor Hillary Clinton has exactly made a major contribution to the theory of international relations," he says.

Ferguson, who remains in good health, is currently doing the research for the second and concluding volume, which will take in the opening up of US relations with China.

"Volume two will probably take me another three years, so don't hold your breath."