Lessons learned from Vietnam, as told by Robert McNamara

1. We misjudged then — and we have since — the geopolitical intentions of our adversaries … and we exaggerated the dangers to the United States of their actions.
2. We viewed the people and leaders of South Vietnam in terms of our own experience … We totally misjudged the political forces within the country.
3. We underestimated the power of nationalism to motivate a people to fight and die for their beliefs and values.
4. Our judgments of friend and foe alike reflected our profound ignorance of the history, culture, and politics of the people in the area, and the personalities and habits of their leaders.
5. We failed then — and have since — to recognize the limitations of modern, high-technology military equipment, forces and doctrine…
6. We failed as well to adapt our military tactics to the task of winning the hearts and minds of people from a totally different culture.
7. We failed to draw Congress and the American people into a full and frank discussion and debate of the pros and cons of a large-scale military involvement … before we initiated the action.
8. After the action got under way and unanticipated events forced us off our planned course … we did not fully explain what was happening and why we were doing what we did.
9. We did not recognize that neither our people nor our leaders are omniscient. Our judgment of what is in another people's or country's best interest should be put to the test of open discussion in international forums. We do not have the God-given right to shape every nation in our image or as we choose.
10. We did not hold to the principle that U.S. military action … should be carried out only in conjunction with multinational forces supported fully (and not merely cosmetically) by the international community.
11. We failed to recognize that in international affairs, as in other aspects of life, there may be problems for which there are no immediate solutions … At times, we may have to live with an imperfect, untidy world.

Good thing we learned those valuable lessons in the 70s.