31 May LA Times commentary - The Lessons of Vietnam by Henry A. Kissinger.

The Iraq war has reawakened memories of the Vietnam War, the most significant political experience of an entire American generation. But this has not produced clarity about its lessons.

Of course, history never repeats itself exactly. Vietnam and Iraq are different conflicts in different times, but there is an important similarity: A point was reached during the Vietnam War when the domestic debate became so bitter as to preclude rational discussion of hard choices. Administrations of both political parties perceived the survival of South Vietnam as a significant national interest. They were opposed by a protest movement that coalesced behind the conviction that the war reflected an amorality that had to be purged by confrontational methods. This impasse doomed the U.S. effort in Vietnam; it must not be repeated over Iraq.

This is why a brief recapitulation of the Indochina tragedy is necessary...